Democrat John Edwards is trying to turn the Democratic presidential race into a referendum on honesty and integrity, areas where polling has shown that voters are divided about Hillary Rodham Clinton.

The argument marks a shift in a race where Edwards and Clinton's other Democratic opponents have criticized her stance on policy but usually have avoided taking on her character directly. In an interview Monday with The Associated Press, Edwards said Clinton is part of a corrupt Washington system.

"Good people are caught up in this system, and I've given some examples of the places that I think she's caught up in it," Edwards said. "And I also, secondly, think that she continues to defend it. And I don't think you can bring up the change this country needs if you defend a corrupt system that doesn't work.

"The closer we get to the election and the more people move past celebrity and to the issues such as honesty, integrity and who can actually bring about change, I think they are going to pay very close attention to those questions," Edwards said while riding in a minivan between campaign stops.

Edwards is a former trial lawyer with a penchant for making effective closing arguments that are strong on emotion, and he is likely to press his case when the Democrats meet for a debate Tuesday night in Philadelphia. His shift against Clinton comes as she is leading in every national and state poll.

Clinton leads even though a study out Monday found that she got some of the most negative media coverage of the White House field. And she's in front even though Edwards has been ramping up his criticism of her since the summer, particularly on her ties to lobbyists.

She also has been subject to frequent character attacks from Republican presidential candidates. Democratic consultant Stephanie Cutter said that is a safer move since it has the intended effect of firing up the GOP electorate against a well-known Democrat.

"Character issues are the most powerful attack lines in a general election, but they are risky in a primary, especially when questioning the honesty of someone like Hillary Clinton who remains among the most popular in the party," Cutter said. "It can backfire. At the same time, the Clinton campaign would be wrong to ignore it."

A poll conducted earlier this month for CNN found clear majorities of voters see Clinton as a strong and decisive leader; as likable; as able to work well with both parties; and as caring about their needs. But on questions of character, voters were split roughly in half when asked whether she is honest and trustworthy; whether she shares their values; and whether she is a person they admire.

Edwards suggested Clinton is mostly running for president out of personal ambition.

"She said it, didn't she?" Edwards said. "Wasn't her phrase early on in her campaign, 'I'm in it to win?"'

He acknowledged that personal ambition played a role in his 2004 presidential campaign, but he said it is less so in this bid.

"Being honest, you can never say personal ambition doesn't play a role," Edwards said. "But I do think that I'm driven by something different. I'm driven by making this country work for the kind of people I grew up with."

Clinton's campaign responded by pointing to what it said are differences between Edwards' first and second White House bids.

"Senator Edwards' entire campaign has devolved into a daily routine of negative personal attacks against Senator Clinton," said Clinton spokesman Phil Singer. "He's a far cry from the John Edwards of 2004 who rose to prominence by decrying personal attacks against other Democrats."

Campaigning in New Hampshire Monday, Edwards repeatedly referred to the importance of integrity in the presidential race. In a speech at St. Anselm College that was billed as setting the theme for the next two months of the campaign, Edwards suggested donations from lobbyists would turn a Clinton presidency into "a Democratic version of the Republican corruption machine."

Edwards wrapped up a town hall in Exeter by arguing that New Hampshire voters have a special responsibility to repair damage done by the Bush presidency and elect a leader they can look in the eye and trust, regardless of their policy positions.

"You're in a position to understand and evaluate the honesty, the sincerity and the integrity of the presidential candidates," he said. "All of this other stuff becomes unimportant if you don't have a president that you believe will tell you the truth even when it's hard, and a president who is honest and sincere and that you can count on. I don't know about you, but I'm not interested in having the next great politician as president."

Edwards has been focusing his criticism almost entirely on Clinton, ignoring the threat from opponent Barack Obama even though all three are within striking distance of each other in polls of Iowa caucus-goers.

Edwards said that is because he and Obama often are on the same page, although they disagree on some matters.

"For the most part, I think we're most closer in our views and perspectives," Edwards said.