The sense that New York Senator Hillary Clinton presidential campaign is going from strength to strength grew Sunday as a new Des Moines Register poll showed her moving into the lead in the first caucus state of Iowa. And Clinton’s position there got a boost over the weekend as Iowa Democrats who still doubt her anti-war credentials were reassured by none other than 1972 Democratic presidential nominee George McGovern.

McGovern, an anti-Vietnam War icon who has been a far more consistent foe of the Iraq War than Clinton, heartily endorsed the 2008 Democratic front runner on a day when the Register poll suggested that the New York senator might actually win the caucuses that are expected to define the course of the race for the Democratic nod.

McGovern does not cut Clinton a lot of slack for her 2002 vote to authorize Bush to attack Iraq. The former senator bluntly declares that it was “a mistake to support that war at any time.”

But McGovern argues that there are few “mistake-free” candidates and says that Clintonhas moved toward what he sees as a “pretty good” position on the war. “She knows that’s its gotta be ended,” the former senator says. “She said if by any chance Bush were to continue the war that after 2008 she’d terminate it. That’s about all you can expect.”

This is a debatable point. But it is fair to say that the willingness of liberals such as McGovern to make their peace with Clinton is reflected in her improving position in Iowa and elsewhere.

According to the Register poll of Iowans who are likely to participate in the first-in-the-nation caucuses, Clinton is now at 29 percent. Former North Carolina Senator John Edwards, who has made little secret of the fact that he must secure a first-place finish in Iowa to continue as a serious contender, was at 23 percent. Most of Clinton’s gain in the survey appeared to be the expense of Edwards, who fell 6 points from his position in May poll for the Register.

Illinois Senator Barack Obama, who runs closest to Clinton in national polls, was at 22 percent in Iowa. Rounding out the field in the Hawkeye state were New Mexico Governor Bill Richardson at 8 percent and Delaware Senator Joe Biden at 5 percent, with Connecticut Senator Chris Dodd, Ohio Congressman Dennis Kucinich and former Alaska Senator Mike Gravel all at 1 percent or less.

The Register poll has long been the most respected in Iowa. More consistently correct in its assessments than most, in large part because it is constructed to measure signals of strength in the complex caucus process, the survey offered Clinton a good measure of encouragement.

Clinton now leads by a comfortable margin among likely caucusgoers aged 55 and older, who historically have been the steadiest presence at the state’s caucuses. She also leads among likely caucusgoers in union households, displacing Edwards as the favorite pick of labor-linked voters.

Clinton’s strengthening position is Iowa may seem surprising on the surface, as the state’s Democrats are traditionally seen as being more populist and more anti-war than the Democratic front runner. But Clinton has benefited from the fact that more progressive Democrats have begun vetting her candidacy.

Over the weekend, former South Dakota Senator George McGovern, the 1972 Democratic Presidential nominee and a man whose name is synonymous with liberal and anti-war politics, arrived in Iowa to give Clinton an enthusiastic endorsement. “She seems to have a greater feel for the problems of the country. She gets stronger all the time,” McGovern told the crowd at an Iowa City Democratic event that drew a crowd estimated at 1,800 people. “I think that if we can elect her president, she’ll be a greater president even than her brilliant husband.”

McGovern, who had once seemed to be leaning toward Obama, praised the Illinois senator and spoke well of Edwards, but concluded, “We have an old rule of courtesy in the United States: Ladies first.”

While Republican operatives still love to beat up on McGovern and “McGovernism” — despite the fact that the frontrunner for the party’s nomination, former New York Mayor Rudy Giuliani, voted for McGovern in 1972 — the reality is that such attacks have little or no meaning beyond the conservative base. McGovern, who has worked closely with 1996 Republican Presidential nominee Bob Dole on hunger issues in recent years, has at age 85 achieved a comfortable “elder statesman” status.

It was a measure of McGovern’s status, and his value as an endorser, that Clinton went out of her way to appear with the former senator. She told the crowd in Iowa City that he would have a place in her administration, as McGovern did in the administrations of Bill Clinton and, briefly, George W. Bush. The South Dakotan

Among grassroots Democrats in Iowa who recall his past campaigns, however, his endorsement of Clinton has value. The former senator remains an exceptionally well-regarded figure among liberals in Iowa and other states of the upper Midwest. A strong showing in the 1972 Iowa caucuses gave the former senator an important boost in his race for the nomination that year. When McGovern made a long-shot bid for the 1984 Democratic presidential nomination, he shocked national pundits by securing a solid finish in the caucuses, ahead of Ohio Senator John Glenn and others who were considered more serious contenders.

At the Johnson County Democratic picnic where McGovern and Clinton appeared together, signs read “JoCo (Johnson County) Loves McGovern,” and Clinton backers held “McGovern/Clinton” signs. When the former senator appeared at the Johnson County Fairgrounds, the crowd delivered what was easily the noisiest ovation of the day that featured remarks by Clinton, Edwards, Dodd, Kucinich, Richardson and actor Forest Whitaker, who spoke on behalf of Obama.

George McGovern’s endorsement of Clinton in Iowa City on Sunday came as part of a weekend of campaigning he did across Iowa on the Democratic frontrunner’s behalf. On several of the stops, he was accompanied by Massachusetts Congressman Jim McGovern, who is no relation but who shares the former senator’s strong anti-Iraq war views.

Hard-core foes of the war in Iraq will still have a hard time voting for Clinton in Iowa or elsewhere. While she is a strong critic of Bush’s management of the war, she remains a weak proponent of strategies to bring U.S. troops home from the conflict. But among old-school Iowa Democrats, the McGovern seal of approval will help.