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Bickering to the last, Democrats traded insults Sunday as they reached for the finish line in a close and caustic Iowa caucus race, the first step toward picking President Bush's rival.

"We are going to win," said Rep. Dick Gephardt (search), echoing the hopes of former Vermont Gov. Howard Dean (search) and Sens. John Kerry (search) and John Edwards (search) in a contest impossible to predict.

While four rivals raced between Iowa's state lines, Dean sought to regain the political initiative with a trip to Georgia, where former President Carter answered campaign critics of Dean, and a surprise guest upon his return. After months in the political shadows, Dean's wife, Judy, was making her first appearance on the campaign trail.

In the closest caucus race since 1988, when Gephardt won by 4 percentage points, polls showed the four candidates in a statistical tie, but that didn't stop strategists from handicapping.

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Democrats agree that Dean and Gephardt have the strongest organizations, traditionally a key in the complicated caucus system, but Kerry and Edwards had the momentum in the race's final week.

Confidence abounded in the Dean campaign. "We think we have the best organization," the candidate told ABC's "This Week" in a taped interview, while thousands of backers knocked on doors of potential voters.

Hopes were high in the Kerry and Edwards campaigns, though aides said they couldn't predict whether their outgunned organizers could deliver enough votes on a cold caucus night.

Doubts seeped into the Gephardt camp, where a defeat would end all hopes for the presidency. The 14-term Missouri congressman, in his last political race, showed no sign of quitting, rallying hundreds of union backers in the state capital.

"I don't need this job; I don't need this title," Gephardt said. "But America needs a leader who comes from a life experience of the people. Forget about me, I'm unimportant in this, I'm an instrument."

Kerry, his voice hoarse after long days of noisy campaign rallies, mingled his war-hero pitch with a sharply populist assault on "powerful monied interests," previewing for a crowd in Waterloo, Iowa, a theme he will use next week in New Hampshire to court independents.

Entering the year a clear front-runner, Dean lost his lead in Iowa after a rough week of political combat that has threatened his lead elsewhere. Stung by criticism of his record on race relations, Medicare and trade, Dean said he was tired of being the party's "pin cushion," and suddenly looked weak to voters drawn to his take-no-prisoners image.

Gephardt gambled with an ad that questioned Dean's integrity. It worked -- Dean's approval rating dropped and voters fell from his camp -- but the strategy had an unintended effect. Suddenly, Edwards looked optimistic, Kerry presidential.

The result was no clear favorite, with 45 pledged delegates up for grabs in Iowa. Out of 4,322 total delegates, 2,162 gives a Democrat the nomination.

A Des Moines Register poll showed just 5 percent of potential voters undecided, but nearly half of those who have candidate preferences saying they could still be persuaded to vote for somebody else.

Leaving an Edwards speech, Bettie Spaight of Cedar Rapids said she was still looking.

"If we could have a little bit of each of them in one candidate, that would be ideal," Spaight said.

Dean sought to reclaim the initiative Sunday. His wife's appearance was designed to soften his image while Carter addressed deeper political problems.

Rivals dismissed the campaign stops as gimmicks, keeping steady aim on Dean's policies and qualifications.

"This is not the time for on-the-job training," Kerry told ABC's "This Week" as the candidates made the rounds of television news shows.

Gephardt accused Dean of flip-flopping. Kerry criticized Gephardt and Dean for advocating tax increases for the middle class. Even Edwards got in the act, taking a swipe at Wesley Clark, who skipped Iowa to focus on New Hampshire and its Jan. 27 primary.

"They're not quite as vicious to each other as they are to President Bush," Republican Party chairman Ed Gillespie said at a downtown hotel. "But they're getting close."

In New Hampshire, former Sen. George McGovern, the 1972 Democratic nominee, endorsed Clark.

In Georgia, Carter stopped short of an endorsement, but answered critics of Dean's shoot-from-the-lip style.

"The fact that he was a strong and open advocate of peace whenever possible instead of war, and his outspoken nature, sometimes saying things that might have to be retracted, which I had to do as well when I ran for president, has made it very harmonious between me and him," Carter said.

Kerry spokesman Michael Meehan said the senator also had been invited by Carter to visit. "We wanted to stay with Iowans," he said.

Dean, an infrequent church-goer who only recently talked about his faith in public, joined Carter for services in Plains, Ga., then called the former president a "moral model."

Carter dismissed suggestions that a northerner such as Dean can't win in the South. Carter noted that he and Dean share an affinity with Job, who is beset by tragedies in the Bible.

"I couldn't believe all the accusations leveled against me" in politics, Carter said, echoing Dean's complaints.

Long-shot candidate Dennis Kucinich also focused on Iowa on the final day before the caucuses.