MANCHESTER, N.H. – Democrat Barack Obama on Monday sharpened his critique of lead rival Hillary Rodham Clinton, warning against a return to “divisive, special interest politics” that had demoralized the country even before President Bush took office.

“As bad as this administration has been, it’s going to take more than just a change in parties to truly turn this country around,” Obama told supporters at a Labor Day rally.

“George Bush and Dick Cheney may have turned divisive, special interest politics into an art form, but it was there before they got to Washington. If you and I don’t stand up to challenge it, it will be there long after we leave.”

It was the latest volley in the “change versus experience” debate that has dominated the dialogue between Clinton and her top rivals in recent weeks. On Sunday, Clinton unveiled a new campaign speech where she argued that only a president experienced in the ways of Washington could bring about real political transformation.

Without mentioning Clinton by name, Obama struck back hard at that argument.

“There are those who tout their experience working the system in Washington,” Obama said. “But the problem is the system in Washington isn’t working for us, and it hasn’t been for a very long time.”

Obama, who has spent much of the campaign answering questions of whether he is experienced enough to be president, ticked through his years as a community organizer and consensus builder in the Illinois legislature and now in the Senate. But he also sought to frame his hope-driven message as an antidote to the cynicism of political insiders.

“A lot of people who’ve been in Washington a lot longer than me, they’ve got better connections, they go (to the) right dinner parties, they know how to talk the Washington talk,” he said. “I may not have the experience Washington likes but I believe I have the experience America needs right now.”

With Clinton still riding high in most polls as the fall campaign was set to begin in earnest, both Obama and John Edwards have stepped up their claim that Clinton is too cautious and too conventional to bring real change to Washington.