KEOKUK, Iowa - Sen. Joseph R. Biden Jr. paced before the fireplace in Susan Dunek's living room and chopped the air with his hands as he outlined the legal scholarship on the war-powers clause of the Constitution, part of his answer to a voter's question about the invasion of Iraq.

Then he stopped himself.

"This is boring," the Delaware Democrat said.

"No, it isn't," protested his audience.

"You all are amazing," the senator said. "You're lovely."

In his second campaign for president, Biden, 65, is speaking his mind, giving Iowa voters full paragraphs of context instead of sound bites, making issues seem clear rather than simple. He seems like a man liberated from the promise and tragedy of his past, serene in the shadows thrown by the star wattage of fellow senators Barack Obama and Hillary Rodham Clinton, the former first lady.

To be sure, Biden is flirting with fourth place in what has been, up to now, a three-person Democratic race. Iowans appear to be warming to him in the final days before the Jan. 3 caucuses, the first contests in the race: His crowds are growing, they're listening intently, and many people stay behind for a picture, an autograph, or simply to touch him.

Whatever happens, Biden has earned respect from voters and pundits as serious and thoughtful, a kind of redemption 20 years after his first presidential campaign of airy rhetoric blew up amid accusations of plagiarism. A pair of brain aneurysms nearly killed him in 1988.

By then, he had already endured the death of his wife and young daughter in a car accident in Wilmington just after being elected to the Senate in 1972 at age 29. His two sons were injured.

These days, Biden doesn't let much get him down. It's probably the last hurrah for his White House ambitions, and he's enjoying the ride.

"It's so much easier this time, because I really, genuinely know what I believe and what I would do as president - I have a comfort zone," Biden said in an interview on a recent swing through eastern Iowa. "There's not any nobility about it, it's just that I'm OK."

When he ran in 1988, Biden was 44, the candidate of idealism who summoned his baby-boom generation to change the world. It seemed self-conscious to many.

"This is the first campaign I've been in that I haven't run myself," Biden said. "I'm usually the guy who says, 'Let me see the brochure, let me write it, let me change it.' "

He can still wax on (and on) and likes to quote poet Seamus Heaney's plea to make "hope and history rhyme," but Biden mostly flashes detailed expertise on constitutional law and foreign policy, and his diplomatic contacts. For instance, he told several audiences of a recent call from Pakistani President Pervez Musharraf.

Biden has blazed a trail on Iraq, supporting war funding while pushing to end the fighting by splitting the country into semi-autonomous zones along sectarian lines.

Even his opponents have tipped their hats to his gravitas, inspiring a YouTube ad that showed clips of three Democratic rivals saying, "Joe is right."

Indeed, his foreign expertise has been praised so much that Biden constantly faces suggestions he's really positioning himself to be secretary of state. He brushes that aside as condescending.

"He doesn't have the general appeal, the celebrity, but I've always admired his experience," said Ray Goeke, 79, a retired music teacher from Keokuk. "He's been dead right on Iraq. It's just unfortunate more people don't listen to him."

Rank-and-file Democrats seem to love his tough talk. In recent weeks, Biden has threatened to push impeachment of Vice President Cheney and President Bush - in that order - if they invade Iran.

"He's got a lot of guts, reminds me of Harry Truman," said Paul Neimann, 66, a retired factory worker in Burlington, Iowa.

"The American people don't give a darn about any of this stuff that's going on up here," Biden said during a November presidential debate last month, referring to Clinton's complaints she was being picked on.

In an October debate at Drexel University, he cut GOP candidate Rudy Giuliani, the former New York mayor, to size: "There's only three things he mentions in a sentence - a noun and a verb and 9/11."

Wit is a double-edged sword, of course, and Biden drew unpleasant memories of his garrulousness when in January, on the day he was announcing his candidacy, an interview appeared in which he said Obama was rising in the opinion polls because he is "the first mainstream African American who is articulate and bright and clean and a nice-looking guy" to run for president.

There have been no notable gaffes since; Biden is more disciplined than in the past.

Biden travels Iowa with an aide or two in a Chevrolet Suburban, with no escort cars, no press bus, few klieg lights, and no boom microphones attending him. No fuss, like Iowans themselves.

While Obama has Oprah, and Clinton has the former president, Biden's entourage on this trip included his son Hunter, daughter-in-law Kathleen, and his granddaughter, 9-year-old Finnegan, introduced as "the love of my life."

Unlike Clinton or Obama, whose strategy rests on bringing new voters to the caucus process, Biden aims to capture more reliable hard-core caucus goers.

Polling by other campaigns has picked up strong pockets of support for Biden in some rural regions and in the ethnic, majority-Catholic industrial towns along the Mississippi River in eastern Iowa.

"The core Biden constituency is news consumers, people who are paying attention to the world - and they will caucus," said John Marttila, who has advised Biden since 1972.

Biden started advertising for the first time on Iowa TV Dec. 12, and he has a strong organization with support from many state legislators. While he does not expect to come in first here, Biden believes he will beat expectations.

Iowans are notorious for deciding late, and the caucus process drew only 120,000 Democrats four years ago and 62,000 in 2000 - a minuscule percentage of voters. Because of the way the process works, concentrated support in a few areas can produce delegates.

"Over a year, you can shake the hand of everybody that's going to caucus for you," said David Redlawsk, a professor and pollster at the University of Iowa.

And so Biden motors on, answering every question at length and stopping to greet people as his son tries to herd him to the next stop.

Don Dodge grabbed Biden's hand on the way out of a cold conference room at the Iowan Motor Lodge in Fort Madison, pledging to caucus for him.

"Don't let this guy get out of here without his phone number," Biden said, motioning to an aide.