Delivering a major address in April before a portrait of George Washington and busts of John Adams and Thomas Jefferson in Boston’s historic Faneuil Hall, John Kerry must have felt as though he was back running for President. But on the thirty-fifth anniversary of his stirring testimony before Congress as a representative of Vietnam Veterans Against the War, Kerry was invoking a theme downplayed throughout his 2004 campaign and confronting the issue that bedeviled his candidacy: the war in Iraq.

“As in 1971, this is another moment when American patriotism demands more dissent and less complacency in the face of bland assurances from those in power,” Kerry told a crowd of 800 full of fellow vets and Democratic activists. “As in Vietnam, we have stayed and fought and died even though it is time for us to go.” Kerry had recently broken with the Democratic leadership and proposed setting a deadline for Iraqis to form a permanent government and for US troops to leave. According to the Boston Globe, the audience was “wildly enthusiastic”–a phrase not often used to describe crowds listening to the junior senator from Massachusetts. Former DNC chair Steve Grossman called the speech “profoundly presidential,” which is exactly what Kerry once again wants to be.

In the past few months Kerry has presented a side of himself very different from the one the public saw during the 2004 campaign. Freed from the grip of consultants, the spotlight of the national media and the Republican attack dogs, he is looser, clearer and more compelling. Call it the Al Gore Effect. At the end of a presidential campaign, losing candidates either retreat, keep up the good fight or attempt the arduous task of redefining themselves. Kerry’s both fighting and redefining these days.

“The fact of losing so narrowly tends to concentrate the mind,” Kerry tells me in an interview in his Senate office. Only a week after the death of his first wife, the mother of their two daughters, Kerry is surprisingly relaxed and upbeat, frank about his past failures and future aspirations. People close to him certainly sense a change in attitude. Former Senator Gary Hart, a confidant, believes Kerry has circled back to the Vietnam era, recognizing the folly of current US policy and rising to protest against it. “He’s much more outspoken, much more decisive and much less likely to give credit to this Administration,” Hart says.

The notoriously cautious Kerry has gone bold, conveying his views on Iraq and national security through an aggressive schedule of speeches, op-eds and talk-show appearances. Into the void of Democratic Party leadership, he’s speaking for the vocal opposition–even endorsing Senator Russ Feingold’s resolution to censure President Bush. Kerry’s been written off before and is rising from the political graveyard yet again. “What does he have to lose now?” says Kerry biographer Douglas Brinkley. “He might as well go for broke.”

That wasn’t always Kerry’s attitude. Upon returning to the Senate after the 2004 election, he gave Bush some space. Though he blocked drilling in the Arctic National Wildlife Refuge with a threatened filibuster, Kerry focused for the most part on noncontroversial issues like children’s healthcare and a bill of rights for military families. Over time, he grew more outspoken, renaming the Bush Administration “the Katrina Administration” after the devastation of New Orleans. Soon he was plunging into intraparty squabbles, and he led a failed attempt to filibuster Samuel Alito’s Supreme Court nomination.

And after years of vacillation, he has found his voice on Iraq. He’s visited the country three times since the election, on each trip growing more dismayed by the lack of progress. After his second visit Kerry gave a major speech at Georgetown University, in October. “It is time for those of us who believe in a better course to say so plainly and unequivocally,” he declared. For the first time, Kerry said he’d made a mistake in voting to authorize the war in 2002 and suggested that the bulk of American forces be withdrawn by the end of 2006. On his third trip to the region, this spring, Kerry witnessed a war between insurgents and occupiers transforming into a civil conflict, with US troops caught in the middle. Claiming that “Iraqis have only responded to deadlines,” Kerry suggested two of them in a New York Times op-ed: an immediate withdrawal if Iraqis don’t form a government by May 22, or a US exit by the end of this year if they d0, in coordination with a Dayton Accords-style international summit. Of all the votes he’s cast in the Senate, Kerry told Tim Russert on Meet the Press, his Iraq vote is the one he’d most like to take back. As one Kerry adviser wryly put it, “He’s got a position now where there’s no room for nuance.”

Which prompts the question, Why now? Pollster Frank Luntz recently showed a focus group of Democratic primary voters in Iowa and New Hampshire footage of Kerry over the past few months. “Where the hell was this John Kerry?” Luntz says the voters asked him. “Why didn’t he have this passion, this specificity, when we needed him to?” If Kerry had run in 2004 using his 2006 language, Luntz argues, he might be President now.

Kerry has internalized much of this criticism. “You get kicked on your ass, you get knocked flat, you dust yourself off and say, OK, What did I learn from that?” Kerry tells me. “I think I learned a lot.” His endless modifiers have been replaced by short, punchy phrases: “Tell the truth, fire the incompetents, get out of Iraq, have healthcare for all Americans.” He shocked Chris Matthews in a recent interview by answering some questions with just a yes or a no. His new mantra, says Kerry, is “clarity and brevity.”

But policy and rhetoric only partly explain Kerry’s resurgence. His 3 million-plus e-mail list and the $7.5 million he’s given or raised for fellow Democrats since 2004, by far the most of any 2008 contender, solidifies his standing in the party. He even raised $150,000 for Hillary Clinton at a Boston fundraiser last year. Two top operatives from the DNC are overseeing his PAC, Keeping America’s Promise. He’s visited twenty-four states and donated to 110 candidates this election cycle alone. Kerry’s Cash May Buy ’08 Loyalty reads a recent headline in Roll Call.

The presidency is never far from his mind. He freely admits to “thinking hard” about running again. “I have an anger, a level of frustration about the failure of the public sector, that is as burning as when I first got involved in the 1960s,” Kerry says. In March he returned to New Hampshire for his first full day of political campaigning, later penning an op-ed defending the state’s first-in-the-nation primary status. In early May he was back in the Hawkeye State, speaking at a local college and fundraising for Iowa Democrats. “That’s someone who’s running,” says former Kerry campaign strategist and Clinton press secretary Joe Lockhart.

To bolster his national profile, Kerry is launching a think tank–helmed by Gary Hart–to train the next generation of progressive foreign-policy thinkers; coming out with a book on the environment this fall; and scheduling a full plate of political events before the 2006 midterms.

But Kerry’s future cannot be separated from his past. “Democrats have to be willing to give him another hard look,” says Grossman. “It’s a very, very tough hill to climb.” Kerry trails Hillary Clinton 57 to 30 percent among Democrats in a head-to-head matchup, faring worse than his former running mate, John Edwards. He runs no better than 3 percent in online straw polls like Grassroots Democrats don’t want to nominate a previous loser, but if they did, there’s always Al Gore. “The first step of Kerry’s new campaign,” says Brinkley, “is to answer the questions Democrats had about the last one.”