John Edwards on Monday cast Democratic front-runner Hillary Rodham Clinton and her ties to lobbyists as part of a corrupt Washington system that voters should reject in the presidential election.

Edwards railed against the "bankruptcy of our political leadership," an approach that his campaign said would be a major thrust of his efforts in the two months before the first nomination voting. With Clinton appearing to gain strength with every poll, Edwards seemed less to target Republican President Bush's leadership than to cast fellow Democrat Clinton as the insider whom voters should reject

"This corruption did not begin yesterday — and it did not even begin with George Bush, although Lord knows it's been present while George Bush has been president," the 2004 vice presidential nominee said in a speech at St. Anselm College. "It has been building for decades until it now threatens literally the life of our democracy."

"Senator Clinton's road to the middle class takes a major detour right through the deep canyon of corporate lobbyists and the hidden bidding of K Street in Washington," he said. "And history tells us that when that bus stops there, it is the middle class that loses."

Edwards' speech was subdued and direct. The campaign did not set up a flashy venue — he spoke from a podium in a small stripped-down academic auditorium with just one well-worn campaign banner hanging behind him. He read from his remarks and didn't make any attempt to fire up the crowd and draw applause.

He cast the 2008 election as the culmination of an epic struggle between Washington greed and the power of the people. "This is the moral test of our generation," Edwards said.

"Down one path, we trade corporate Republicans for corporate Democrats; our cronies for their cronies; one political dynasty for another dynasty, and all we are left with is a Democratic version of the Republican corruption machine," he said.

Although Clinton has become the clear front-runner in the Democratic primary, she still has a vulnerability — a tight race in the leadoff state of Iowa where Edwards and Barack Obama are within striking distance in current polls. But Edwards' support has dropped, according to a University of Iowa Hawkeye poll out Monday.

The poll had Clinton with 29 percent, Obama with 27 percent and Edwards with 20. Edwards was down six points from August.

Clinton's lead is stronger in New Hampshire, the other early-voting state.

Her campaign said Edwards was turning to attack politics.

"In 2004, John Edwards said, 'If you are looking for the candidate that will do the best job of attacking the other Democrats, I am not your guy,"' said Clinton spokesman Phil Singer. "But now that his campaign has stalled, he's become that guy."

With many voters unhappy with Bush's presidency, Democratic candidates have been promoting themselves as agents of change. That includes Clinton, but Edwards is challenging her and trying to make the race a referendum on who will bring real change to Washington.

"Maybe I have been freed from the system and the fear that holds back politicians because I have learned that there are much more important things in life than winning elections at the cost of selling your soul," Edwards said.

"I saw the chase for campaign money at any cost by the front-runner in this race," Edwards said. "And I chose not join it because the cost to our nation and our children is not worth the hollow victory by any candidate."

The former North Carolina senator said Clinton has refused to accept his challenge not to accept political donations from Washington lobbyists. Clinton has gained strength in the polls since Edwards started making that case several months ago, but he said he thinks it will make the difference in the election.

Singer responded by questioning Edwards' ties to special interests. Edwards has taken donations from industries that employ federal lobbyists, though he doesn't take donations directly from the lobbyists themselves. "If Mr. Edwards is so concerned about the influence of special interests, he should give back the hundreds of thousands of dollars he's taken from health care, securities, and insurance companies," Singer said.