"One candidate will continue the war," she told an audience at Hopewell High School, near Pittsburgh. "One candidate only says he'll end the war. And one candidate is ready, willing and able to end the war."
Obama, campaigning in the Philadelphia suburbs, issued a broad indictment of Republican economic policies and singled out McCain for special rebuke, saying he is willing to "sit idly by" in the face of a national housing crisis.
"It's time to end the Bush-Cheney-McCain policy that tells the American people 'you're on your own,' because we're all in this together," Obama told a crowd at Great Valley High School in Malvern.
Obama also tweaked Clinton, alluding to her husband's presidency while blaming Democrats for being at times "too timid" to confront Washington special interests.
"We let go of the past, but we never finished that bridge to a future of lasting prosperity," he said, a reference to the slogan President Clinton used as he began his second term of office about building a bridge to the 21st century. "Instead, we lost that common stake in each other's prosperity."
Later, at a high school in Levittown, Obama said he would be better at standing up to special interests.
"She doesn't see the problem with lobbyists in Washington," he said. "I don't want to just be the Democrat version of what we have right now."
McCain spokesman Tucker Bounds said Obama and Clinton "are selfishly trying to make political gains in the worst way, by dishonestly saying that John McCain is something that he is not. Americans know that John McCain is the only candidate in this race who has a strong record of fighting to keep their paychecks and communities safe."
For her part, Clinton did not say why she believes Obama would not carry out his pledge to bring most U.S. troops home within 16 months. A campaign news release quoted her as saying, "his adviser says you can't count on that."
It was a reference to a former Obama adviser, Samantha Power, who told a Scottish newspaper that Obama might take longer to end the war if conditions are not favorable. His aides have said Power was not speaking for the campaign, which issued a statement Wednesday saying Clinton's "tired and discredited attack is just the same old politics that won't end this war that she voted to authorize."
Clinton hopes for a solid win in Pennsylvania that would sustain her hopes of persuading the party's superdelegates to give her the nomination despite Obama's lead in pledged delegates, which are won through primaries and caucuses. Obama has closed in on her lead in recent polls in the state, capitalizing on strong support in Philadelphia and its environs.
Her campaign began running a radio ad in Pennsylvania that criticizes Obama for backing an energy bill she opposed and challenging his claim to take on the oil companies.
The two Democrats chose the two leading issues of the day - the economy and the war - to distinguish themselves.
Clinton struck two familiar themes Wednesday: She has the experience and steeliness to be commander in chief, and Obama is a talker, not a doer. His plan to end the Iraq war, she said, "is just words."
She called on President Bush to explain his "end game" plan for Iraq. She also said Congress should be allowed "to review and vote on any long-term agreement" the Bush administration makes with Iraq.
Though Obama did not address the Iraq war during his remarks on the economy, he did link the war and the economy in response to a question.
"The war in Iraq was unwise," he said. "It has piled a mountain of debt that has weakened our economy."
Asked his reaction to Clinton's television commercial that portrays her as best able to answer a 3 a.m. call on national security, Obama said: "The person you want answering the phone at 3 a.m. is the person who read the intelligence reports, who is asking the tough questions about why we want to invade a country like Iraq that had nothing to do with 9/11. And there is only one of the remaining candidates who qualifies on that front," he said.
Asked to comment on the Olympics in China, Obama made no mention of Bush's proposed trip to the opening ceremonies in Beijing, which many human rights activists want him to cancel to underscore concerns about recent unrest in Tibet and questions about China's relationship with Sudan.
Without offering any specifics, Obama said: "In our policy toward China we have not been consistent enough and tough enough."
But he used the question to turn again to the economy.
"If we're running huge deficits and big national debts and we're borrowing money constantly from China, that gives us less leverage," he said. "It gives us less leverage to talk about human rights and it also gives us less leverage to talk about the uneven trade relationship we have with China."
Speaking to a group of Irish-Americans in New York City, Clinton commended British Prime Minister Gordon Brown for announcing he will not attend the opening ceremony of the Beijing Olympics. She called on Obama and McCain to join her in urging Bush to spurn the ceremony as well.
Obama joined Clinton's call later in the day.
His campaign issued a statement in which he for the first time urged Bush to boycott the ceremonies.
"If the Chinese do not take steps to help stop the genocide in Darfur and to respect the dignity, security and human rights of the Tibetan people, then the president should boycott the opening ceremonies," Obama said.
--- Jim Kuhnhenn reported from Malvern, Pa.
