It is good for movements to put pressure on presidential candidates to do the right thing.

I did not learn this from a candidate or from a president, of course. I learned this from the man I have always understood as the most steadily radical and steadily successful political actor of the American 20th century: A. Philip Randolph.

Those who are uneasy with the pressure that activists are bringing to bear on presidential candidates in the already intense 2016 race would do well to remember the strategies and the successes of Randolph, the labor leader who for the better part of 50 years recognized every campaign and every presidential invitation as an opportunity to demand racial justice and economic equality. When #BlackLivesMatter activists challenge a Bernie Sanders or a Martin O’Malley, when climate-change activists challenge a Hillary Clinton, when campaigners against bloated military budgets challenge all the candidates, they do not merely draw attention to vital issues. They have the potential to make candidates and campaigns — and our politics — better.

This is the lesson Randolph taught, along with the lesson that, while it is important to celebrate progress and to recognize allies, activists have a responsibility to keep the pressure on.

“Justice is never given; it is exacted and the struggle must be continuous for freedom is never a final fact, but a continuing evolving process to higher and higher levels of human, social, economic, political and religious relationship,” said Randolph, who in his lifetime became an expert at exacting justice, and at evolving candidates and presidents to higher levels of engagement with the civil rights struggle.

The candidates and presidents often despised the pressure, and their supporters often decried Randolph for upsetting the best-laid plans of contenders and policymakers. But they would eventually thank Randolph — awarding him the Presidential Medal of Freedom among other honors — because they knew he had made them better than they would have been without the pressure.

Randolph never held elected office. After a pair of bids for New York state posts in the 1920s on the Socialist Party line, he rejected repeated pleas that he seek congressional seats or join national tickets. Yet, Randolph and the movements he championed shaped executive orders, helped to forge legislation and defined the debate in his times – to such an extent that his influence resonates to this day, 36 years after the great organizer and agitator died at age 90.

For Randolph, serious political work involved much more than campaigns and elections. Instead of running for president, he organized campaigns that forced those who would be presidents to change positions and in so doing changing America.

As the leader of the Brotherhood of Sleeping Car Porters, a pioneering union of African-American railroad workers, Randolph was the nation’s most prominent African-American labor leader from the 1930s to the 1960s. He used his stature and his connections to arrange meetings with presidents, and with candidates for the presidency. If the meetings did not bring the progress for civil rights that he sought, Randolph brought the pressure of mass movements to the gates of their conventions, to the grounds of their campaign rallies, and to the White House itself.

Frustrated by the failure of the great liberal President Franklin Roosevelt to move to end segregation and discrimination, Randolph in 1940 began with a cadre of young activists to organize the March on Washington Movement that threatened to bring 100,000 African-American activists to the Capitol if FDR did not act. Roosevelt sought to charm Randolph in meetings with the labor leader. Randolph was respectful in his discussions with the president, but he did not bend. He and his allies kept the pressure up and, on June 25, 1941, FDR issued the sweeping Executive Order 8802, which banned discrimination in the defense industries that were gearing up for World War II. After that initial federal action to promote equal opportunity and prohibit employment discrimination, the movement kept the pressure on with mass rallies and organizing to end discrimination in the military, in war industries, in government agencies, and in labor unions — frequently forcing the hand of Roosevelt and his administration.

When the war ended, Randolph and his comrades formed the Committee Against Jim Crow in Military Service, which urged young African-American men to refuse to register for the peacetime draft until the armed forces were desegregated. Even some of his former allies said Randolph had gone too far. But they were just getting started. Pressuring Harry Truman at every turn, Randolph and his allies picketed the Democratic National Convention where the president was nominated for a full term in 1948; inspiring concern that Truman would lose the African-American vote over the issue. Two weeks after the convention finished, the president signed Executive Order 9981, abolishing racial segregation in the military.

Throughout the 1950s, Randolph worked with the great organizer Bayard Rustin and later with a young pastor from Montgomery, Alabama, the Rev. Martin Luther King Jr., to keep the pressure on President Dwight Eisenhower, who in 1957 would sign the first major civil rights legislation since the reconstruction era.

But Randolph was not satisfied. Though he, as a trade unionists, a socialist and a civil-rights champion, had earned a measure of acceptance in the corridors of power, Randolph held to the view he and his comrades had expressed decades earlier: “In this period of power politics, nothing counts but pressure, more pressure, and still more pressure, through the tactic and strategy of broad, organized, aggressive mass action behind the vital and important issues of the Negro.”

To that end, he declared that, “We will have to continue demonstrations.” And he meant it. He and his allies dispatched a young Michael Harrington to organize protests at the Democratic National Convention of 1960, and those protests forced the party to finally begin to distance itself from its southern segregationist wing. In 1963, Randolph called for a “March on Washington for Jobs and Freedom” in order to pressure then-President John F. Kennedy to get serious about passing civil rights and voting-rights legislation – and about using the power of the federal government to protect civil rights activists from state violence in the south. Randolph never let up, he kept pressing for more racial justice, more economic justice, more justice.

Most Americans know little about A. Philip Randolph. As Howard Zinn taught us, the great movers and shakers of our people’s history are often neglected. Yet, we do know that FDR and Truman took steps to end segregation and discrimination, that Kennedy was moved by the March on Washington, and that Kennedy’s successor, Lyndon Johnson, signed a Civil Rights Act and a Voting Rights Act. Some of us know that, after Johnson signed those historic measures, he continued to feel pressure from Randolph, Rustin, King and others to wage the genuine War on Poverty that they demanded with their “Freedom Budget.”

Randolph and the movements with which he worked forced candidates and presidents with whom the labor leader had good relations, and who he often believed to be well-intentioned, to move beyond relationships and intentions to action. In so doing, he made the leaders of the United States better than they imagined they could be at responding to issues of racial disparity and economic injustice. There is some dispute about whether FDR actually encouraged the union leader to create pressure that could not be denied, with the line: “Go out and make me do it.” But there is no disputing that Randolph and the movements with which he worked made FDR and Truman and Eisenhower and Kennedy and Johnson do it, and in so doing played a critical role in changing America.

Nor is there any question that FDR and Truman and Eisenhower and Kennedy and Johnson are better remembered today because they responded to the pressure.

The same goes for the 2016 presidential candidates who are now being pressured. Folks can debate about strategies and tactics, just as they did in Randolph’s day, just as they did when ACT UP activists interrupted “Al Gore for President” events to focus attention on the failure of American policymakers to respond to the crisis of AIDS in Africa.

This summer, #BlackLivesMatter activists have interrupted events and challenged both Bernie Sanders and Martin O’Malley to address issues of policing and racism that they argue must be a focus of the 2016 race.

O’Malley has since released a plan calling for an overhaul of the criminal justice system, in which he declared, “America’s criminal justice system is badly in need of reform. For too long, our justice system has reinforced our country’s cruel history of racism and economic inequality.”

O’Malley, who was criticized for responding to a challenge from activists at the Netroots Nation gathering in Phoenix by saying “all lives matter,” now incorporates the phrase “black lives matter” into his speeches. Citing his record of working to abolish the death penalty — which his campaign white paper correctly identifies as a “racially biased and ineffective deterrent” — the former governor told a National Urban League conference in late July, “Lots of people can talk about criminal justice reform. I have actually done it.”

Sanders went to Texas immediately after the Netroots gathering spoke about the death of Sandra Bland in police custody. References to racial justice and police reforms have been amplified in his speeches. He has hired Symone Sanders, who has served as national youth chair of the Coalition on Juvenile Justice, as his press secretary; and she has hit the ground running with the message: “You know which candidate for president will shut down the private prison industry. You know which candidate will have the courage to fight unjust mandatory minimums and the death penalty.”

Sanders has now incorporated into his core list of campaign proposals a Racial Justice platform that begins with the declaration that, “We must pursue policies that transform this country into a nation that affirms the value of its people of color. That starts with addressing the four central types of violence waged against black and brown Americans: physical, political, legal and economic.”

The Sanders platform makes sweeping commitments to reforms aimed at “eradicating racism in this country,” and it pulls no punches in explaining physical violence against black and brown Americans is “Perpetrated by the State.” “Sandra Bland, Michael Brown, Rekia Boyd, Eric Garner, Walter Scott, Freddie Gray, Tamir Rice, Samuel DuBose. We know their names. Each of them died unarmed at the hands of police officers or in police custody. The chants are growing louder. People are angry and they have a right to be angry. We should not fool ourselves into thinking that this violence only affects those whose names have appeared on TV or in the newspaper. African Americans are twice as likely to be arrested and almost four times as likely to experience the use of force during encounters with the police.”

Sanders, who was in the crowd when Randolph and King addressed the 1963 March on Washington, has as a senator spoken up about police violence and the neglect of urban communities and unemployed youth. This history, distant and recent, has led some Sanders supporters to gripe that he has been unfairly targeted for pressure. But this misses the point that his campaign has been made sharper and more focused by the pressure it has felt — and the pressure it will continue to feel. The same goes for O’Malley. And so it should be for Hillary Clinton and others.

Politics, real politics as opposed to the game show that most of the media perpetuates, involves pressure and it is the response to that pressure that gives us the measure of candidates. No contender for the presidency has ever ended a campaign as he or she began. Campaigns are, and should be, critical pivot points in what A. Philip Randolph understood as the “continuing evolving process to higher and higher levels of human, social, economic, political and religious relationship.” To think otherwise is to accept a politics as usual that reinforces a status quo that needs, on so many issues, and on so many levels, to be shattered.