It has been almost 100 years since Republicans in the US Senate vetoed American membership in the League of Nations. By the most dismal reckonings, what followed was a leaderless League that ultimately collapsed, and a descent by a weakened and traumatized Europe, with millions of its people dead, into a global Depression that opened the door to fascists. And then came another world war. While the arrogance of President Woodrow Wilson, a Democrat, may bear some of the blame in most objective histories, his 1916 dream of a new world order was shattered irreparably because Republican isolationists had taken control of Congress in a 1918 midterm election.

A century later, it could be the United Nations that is in peril. It would be hard to wreck it, as some Republicans would like—one candidate no longer in the race advocated razing it and pushing the debris into the sea—but there is not one GOP candidate now in the race who has been willing to defend the organization or what it stands for, judging from threats made before and during the 2016 primaries. In that atmosphere, if a Republican is elected to the presidency and GOP right-wingers keep control of both houses of Congress, almost certainly the UN and the American role in it will be fair game.

On the Democrats’ side, there has mostly been silence on the campaign trail. But a look back at congressional voting and speaking records reveals something of a surprise. Over recent decades, Bernie Sanders has been a quietly steadfast defender of the UN in important votes, often running against special-interest lobbies and the tide of frequently ill-informed provincialism among both Republicans and some members of his own party. He was repeatedly in a lonely minority.

In the Senate, Sanders voted in 2005 against slashing up to half of US contributions to the UN if a list of substantial management reforms were not made. Four years earlier, he had opposed a measure that would allow the United States to withhold $244 million in delinquent payments to the UN until the United States had its seat restored on the Human Rights Commission (restructured in 2005 as the Human Rights Council). The “UN” does not control elections to the human-rights body, whose members are chosen by member governments.

Sanders has been a member of the Congressional Human Rights Caucus. In 2006, he cosponsored a consensus resolution backing the fielding of a UN peacekeeping force in the Darfur region of Sudan, where casualties in militia attacks, starvation, and displacement over many months have been estimated to be in the hundreds of thousands.

On nuclear issues, which are at the heart of UN disarmament work, Sanders voted against the 2005 US nuclear pact with India, agreeing with other opponents that the deal, pushed by American and Indian corporate lobbies, undermined decades of international efforts to prevent the spread of nuclear weapons. Leading nuclear security experts share this position. India, with a substantial nuclear arsenal, has refused to sign any major agreements on nonproliferation and testing, and has put most of its nuclear facilities off limits to international inspection. In 2015, Sanders supported the Obama administration’s nuclear accord with Iran, saying in a policy paper that the agreement “is far better than the path we were on with Iran developing nuclear weapons capability.”

In 2013, he voted against a Republican-led bid to prevent the United States from agreeing to the UN-sponsored Arms Trade Treaty to control international arms markets. Opponents of the ban had bizarrely tried to tar it as a violation of the Second Amendment to the US Constitution. The Obama administration signed the treaty the same year; it came into force at the end of 2014.

On social issues, Sanders has also been an internationalist for years, not a side of him seen in the current campaign, where he is thought of as weak on foreign affairs. In 2001, he voted against banning or restricting American funding for family planning programs abroad, a leftover of the 1973 Helms Amendment that no president has since tried to wipe off the slate of restrictions affecting women globally. The measure would include lost financing for the UN Population Fund, the world’s largest provider of reproductive health services and commodities, if any group it worked with offered or supported abortion or advocated for it or even counseled about it.

The amendment Sanders opposed passed by a wide margin, positioning the United States in direct defiance of UN policies that advocate abortion and emergency contraception, among other services, for women and girls who have been raped in conflict or the chaos of refugee displacement. Critics say that the United States is in violation of the Geneva Conventions on the rules of war, which the nation has pledged to uphold since the 1950s, because the country is rejecting the universally accepted nondiscriminatory healthcare provisions required by international law.

Hillary Clinton, as secretary of state, enforced and enhanced US spying on UN officials. In 2009, courtesy of WikiLeaks, it was revealed that the State Department under Clinton was asking American diplomats in New York to collect an astonishing amount of information on UN officials, including biometric data, credit card, and frequent-flier card numbers, as well as details about their Internet accounts. Spying has been part of UN life since the organization’s founding, and a lot of countries do it. But still, this directive, which strengthened an earlier one from the Bush administration, shocked people already accustomed to electronic eavesdropping.

Clinton’s supporters could argue, on the positive side, that she has been deeply involved in UN agreements concerning women and children, and she has apparently sought to give the impression that she was instrumental in making or carrying out While House policies on these and other issues. If so, the results did not succeed. In the early 1990s, Clinton, who had done considerable work on children’s welfare and rights all her adult life, promoted the US ratification of the 1989 Convention on the Rights of the Child. In 1995, Madeleine Albright, then the US ambassador to the UN, signed the convention, but President Bill Clinton never sent it to the Senate for ratification, and the document disappeared from the agenda. The United States remains the only UN member country not to have ratified it, and candidate Clinton has made no promises about its future. The past is not an optimistic guide.

In 1995, delegates at the Fourth World Conference on Women in Beijing greeted Clinton as a rock star, but after her spirited declarations there about women’s rights, she did not lead a public campaign to have the United States ratify the Convention on the Elimination of All Forms of Discrimination Against Women, known as CEDAW. Rather, she seems to have deferred to her husband’s general reluctance to take on critics on the political right regarding hot topics.

In a similar crisis-avoidance vein, the United States signed the Comprehensive Test Ban Treaty to control nuclear weapons development but did not vigorously defend it, and it was defeated in the Senate, to the chagrin of the US negotiators at the UN, who had worked tirelessly to make it salable to senators. The Clinton administration also signed the treaty creating the International Criminal Court, but never submitted it for ratification, under threats from the late Senator Jesse Helms, who said it would be “dead on arrival” if it ever got to the Hill.

In 1996, the nadir of US-UN relations in the Clinton era, and the most shocking move internationally, was the sacking of Secretary General Boutros Boutros-Ghali, which was endorsed by both Clintons, out of political timidity if not cowardice. The secretary general was unceremoniously denied a normal second term, amid an ugly standoff within the Security Council, most of whose members were prepared to renew his mandate. But the Republican Right was baying for his head (as, ironically, it would try to undermine his successor, Kofi Annan, a decade later). Republican politicians accused the secretary general of being a threat to American sovereignty—UN “black helicopters” and plans to invade the national parks were among the wildly paranoid and ridiculous accusations. In Washington, Republicans sank to the level of mocking his name: “Booootros, Booootros.” The White House caved. It was an election year.

On to the Republicans in 2016.

Now leading the anti-UN pack in vitriol is undoubtedly Ted Cruz, who is a master of raising alarms and spreading misinformation, intentional or otherwise, about the United Nations and how it works. He has called, most recently last year, for the United States to withdraw from the Human Rights Council (he referred to it as the Human Rights Commission, which it hasn’t been called since 2005) because of a vote condemning Israel for targeting civilians in its 2014 destructive assault on Gaza. Cruz called the council a “hopelessly biased and anti-Semitic institution.”

In a CNN debate, Cruz accused President Obama of wanting “to use the United Nations to bind the United States and take away our sovereignty.” In the Senate, he has blocked approval of diplomatic appointments and recently threatened to disrupt more nominations if Obama goes to the Security Council for approval of the Iran nuclear deal, which involves numerous other nations, not only the United States. He has repeatedly charged that Obama is using the UN to circumvent Congress and “the American people.”

In January, the Right Scoop posted a Cruz ad online claiming that the candidate, as Texas solicitor general in 2008, had “defended US sovereignty and states’ rights when the United Nations ordered a stay of execution for an illegal who had committed murder.” That was the case of Jose Medellin, a Mexican citizen who was convicted in the gang rape and murder of two teenage girls in Houston. Mexico brought a lawsuit against the United States before the International Court of Justice (the World Court), saying that Medellin had been denied consular access. The ICJ agreed, and President Bush accepted the ruling, but Texas argued against the decision all the way to the Supreme Court and won, with Cruz and Texas facing off against the Bush administration, not the World Court, which has no direct jurisdiction in the United States and can rule only against or for governments.

Marco Rubio has used the threat of withholding funds from the UN, where the United States is by far the largest contributor in assessed “dues” for the operating budget and peacekeeping as well as voluntary contributions to a host of UN agencies. In 2013, he proposed imposing a long list of reform measures on the UN. Introducing a bill as a member of the Senate Foreign Relations Committee, he summed up the UN in one memorable sweep: “While at some times throughout its history the UN has played an effective role in global affairs, today it is plagued by ineffective leadership, excessive bureaucracy, ethical abuses, its spending and transparency problems.”

John Kasich, whom a number of political commentators and editorial writers see as a serious candidate in a raucous, vulgar gang of insult-throwers, is not a fan of the UN either. In a conversation about foreign policy with Sean Hannity on Fox News in July 2015, he started by saying he really had nothing to learn from the world. “I’ve had a lot of experience. I don’t need to like go places to learn, OK? I sat on the Defense Committee,” he said. “If I take a trip, it’s going to be to discuss America, not to go over there and to learn about all these countries.”

In the interview, he was as belligerent as his fellow Republican candidates, if in less bombastic terms. He wouldn’t rule out ground troops in a tougher fight against the Islamic State. He favors sending arms to Ukrainians under pressure from President Vladimir Putin. He was more equivocal in the Iran nuclear accord. Although he called it “a very bad agreement,” he stopped short of demanding a repeal until more is known about its effects. “And if it’s a bad deal, we absolutely will have to do what’s in the best interests of the United States of America, not in the best interest of the United Nations,” he said.

Donald Trump is in many ways a more complicated character where the UN is involved. He knows more about the organization than his peers, but his interest is often that of a real estate agent or property developer, never a diplomat or foreign-policy thinker. When the UN began drawing up plans to renovate its headquarters more than a decade ago, Trump jumped in to say that he could save the organization a billion dollars, more than half the estimated cost. He questioned the decisions of people he called “bureaucrats” out to get rich from a higher price tag, but supported then-Secretary General Kofi Annan for backing a renovation, particularly since the Secretariat and other buildings no longer met New York City health and safety standards. “I have a lot of respect for the secretary general and know he is going to do the right thing,” Trump said in an interview with ABC News. He did not win a bid.

Trump is well known to have tried to lure diplomats from around the world into moving their residences or offices in his luxury 90-story condominium building, Trump World Tower, across First Avenue in Manhattan from UN headquarters. In general, he has sought to develop relationships with prominent ambassadors from countries where he may have business interests.

In the light of his understanding of the UN and how it works, Trump would be less likely to weaken it from Washington and more prone to trying to control it directly in New York. Stephen Schlesinger, author of Act of Creation, a history of the UN’s founding, said that Tea Party right-wingers might be encouraged by the opportunity of a Trump presidency in their campaign to defund and cripple the UN, but there is another possibility. “My own theory is that Trump in the White House, given his glorious ego, will seek to control the UN as sort of a world master,” Schlesinger said, in an email interview. “He will not be happy just running the USA, he will want world domination manifested through the UN. It’s in his nature.”

Trump has disgusted and frightened at least some Americans with his careless talk about “bombing the shit out of ISIS,” greatly empowering the US military without a hint of understanding how complex world crises are, and making proto-fascist pronouncements about taking charge of America, riding roughshod over laws and institutions. Globally, this kind of bravado alienates foreign nations and US allies more than it impresses them. His threats to build a wall along the Mexican border and to bar all Muslims from entering the United States have caused revulsion in the UN community.

Uncharacteristically for UN officials, the organization’s leaders have heaped public criticisms on his proposed policies and his reckless and dangerous views of the world. In November 2015, Secretary General Ban Ki-moon’s spokesman, Stéphane Dujarric, was asked at a regular briefing for reporters about growing international abhorrence and outrage. He said:

I’m going to try very hard for the next year almost not to insert the secretary general into the US presidential campaign. That being said, I think the secretary general, deputy secretary general, High Commissioner for Human Rights [and] High Commissioner for Refugees could not have been clearer in the language they used to say that refugees and migrants cannot be discriminated against on the basis of religion, on the basis of nationality, ethnicity—on anything. People who are fleeing war, who are fleeing violence—migrants—all need to be treated with dignity, with respect to their rights as they have them under international law.

Benn Steil and Max Boot are conservative commentators, yet in a bruising article in The Weekly Standard on February 26 they jointly sounded a warning about the havoc in the world and the terrible destruction of US relations with allies and foes alike that would follow if Trump were elected and operated on his ill-thought-out threats. “Trump has already done considerable damage to America’s reputation with his crude, bombastic and often ugly rhetoric,” they wrote. “American standing, as measured in both ‘soft power’ and more traditional realpolitik terms, would suffer far more if he were to become commander in chief. A Trump presidency threatens the post-World War II liberal international order that American presidents of both parties have so laboriously built up—an order based on free trade and alliances with other democracies.”