By the time John Edwards got his first chance to speak in the latest Democratic debate, six of his seven rivals had answered questions, and both Barack Obama and Hillary Rodham Clinton had proclaimed themselves agents of “change.”

Later, however, Edwards had some strong moments, including speaking out with emotion for universal health care and vowing to fight “big insurance companies, big drug companies, big oil companies.” Yet most post-debate analysis focused on Clinton and Obama, a familiar pattern in the Democratic race.

When the former North Carolina senator began this presidential bid, it was widely believed that, like many repeat candidates, the experience of his unsuccessful first try would help him. But, like Sen. John McCain on the Republican side, the second time has not proved to be a charm.

His hopes depend almost entirely on keeping his tenuous lead in the Iowa caucuses, where he ran second in 2004. But that strategy is risky and could be disastrous if even a small number of his Iowa supporters decide later this year against voting for a candidate with dubious national prospects.

To be fair, only some of Edwards’ problems are of his own making. Many reflect the changed circumstances of this political landscape compared with four years ago. They include:

l In 2004, Edwards was the year’s most attractive new face, dazzling crowds with his trial lawyer oratorical skills. But he was unimpressive as the party’s vice presidential nominee, especially in debating Dick Cheney. Now, Obama is the hot newcomer, attracting large and excited crowds. And Clinton, as the first major female candidate, seems more exciting than Edwards.

l The Democratic field is much stronger than four years ago. It has two heavyweight contenders in Clinton and Obama, and even the second tier has major figures. New Mexico Gov. Bill Richardson dwarfs all in experience, having been a House member, a governor, a Cabinet member and U.N. ambassador. Sens. Joe Biden of Delaware and Chris Dodd of Connecticut are major Senate players and veterans of more than 30 years in Congress. As a one-term former senator, Edwards has the least elective experience.

l Clinton and Obama are big vote-getters from big states with strong support in key party constituencies, Edwards is a white Southerner in a party whose Dixie base has eroded, enjoys only modest popularity in his home state and is not the top choice of any major constituency.

l Edwards has handicapped his candidacy with mistakes. He undercut his effort to champion the fight on poverty by building a lavish North Carolina estate, accepting large fees from a New York hedge fund and for a college speech on poverty, and charging his campaign for the services of an expensive hair stylist.

Ironically, his campaign’s biggest boost followed his wife, Elizabeth’s, disclosure in spring that her cancer had recurred. That may explain why the campaign has recently given Mrs. Edwards greater visibility, including unusual access for an interview about her fight against cancer in The Wall Street Journal and a starring role in a campaign commercial.

But her enhanced role backfired when Edwards said her husband was a better advocate on women’s issues than Clinton.

Edwards’ frustration over his inability to gain traction surfaced recently when he was overheard suggesting to Clinton the advantage of limiting the number of debate participants, presumably to front-runners. That prompted one rival, Rep. Dennis Kucinich of Ohio, to suggest they were trying to “rig” the election, a charge both denied.

Monday night’s debate underscored his problem: the difficulty in sticking out in a field dominated by Clinton and Obama.