On Saturday, she traveled from Cincinnati to another rally on the outskirts of Dayton, then flew to a conference of African Americans in New Orleans. After an evening stop in Houston, she planned to return to Washington.
Her recent rallies have attracted as many as several thousand. But over the last week, Obama has drawn an estimated 15,000 in Dallas, 18,000 in Houston and 20,000 in Austin.
At the Dallas rally Wednesday, he was introduced as "the one man with the integrity of President Kennedy . . . the morals of Dr. Martin Luther King, the virtues of Cesar Chavez." The crowd even cheered when he blew his nose mid-speech.
Clinton, who has fallen well behind Obama in fundraising, faces an uphill battle to overcome his lead in delegates to the party's national convention.
Her negative turn on Saturday came amid discord among her advisors on a strategy to revive her candidacy.
Tad Devine, a Democratic strategist not aligned in the presidential race, said the tug of war shows in her latest shift. "It's very hard to deliver a message when the tone changes day to day," he said. The likelihood of a Clinton recovery is "very low," he said.
Clinton has tried to sully Obama before. She ran TV attack ads before the Wisconsin primary last Tuesday, but failed to avert a lopsided defeat.
In Cincinnati on Saturday, Clinton stepped up efforts to define Obama as a gifted speaker with a thin resume.
"That is not the new politics that the speeches are about," Clinton said of the mailings. "It is not hopeful. It is destructive, particularly for a Democrat."
One of the mailings says that Clinton's healthcare plan would force Americans to buy healthcare coverage even if they could not afford it.
"Just because Sen. Obama chose not to present a universal healthcare plan does not give him the right to attack me because I did" propose one, Clinton said. She said Obama's mailing echoed the positions espoused by insurance and drug companies, giving "aid and comfort" to them and their Republican allies.
"So shame on you, Barack Obama," she said. "It is time you ran a campaign consistent with your messages in public. That's what I expect from you. Meet me in Ohio. Let's have a debate about your tactics."
Clinton and Obama are scheduled to debate Tuesday night in Cleveland.
Obama jabbed back Saturday night at a raucous rally in Akron, where an estimated 5,000 braved the cold to hear him speak. But he did not approach his rival in volume or intensity.
