Obama seemed to ignore the former first lady, turning his political guns on presumptive Republican nominee John McCain to blast his stands on the Iraq war and the economy.
Clinton has come under pressure from Obama supporters in recent days to drop out of the contest because of what some see as the Illinois senator's insurmountable delegate lead with just 10 primaries and caucuses to go.
But the former first lady showed no signs of quitting as she focused on job creation and challenges to the U.S. economy at campaign appearances across Pennsylvania, which holds the next primary contest on April 22 with 158 delegates at stake.
Pennsylvania and other states holding upcoming primaries, including Indiana and Kentucky, have suffered the loss of manufacturing jobs in recent years and have yet to transition to new industries and other ways of expanding their economies.
Obama tried to look past his nomination battle with Clinton to the general election matchup with the Republican nominee-in-waiting John McCain, who has been playing up his foreign policy and national security experience.
Obama picked up the endorsement of former Indiana Rep. Lee Hamilton, the top Democrat on the panel that investigated the Sept. 11 attacks, which could boost his national security standing.
Hamilton is the highest profile Indiana Democrat to back Obama before the state's May 6 primary.
The former Indiana lawmaker served on the House Foreign Affairs Committee during his more than three decades in Congress and also was co-chairman of the Iraq Study Group, a bipartisan commission that assessed U.S. policy in Iraq.
The Pennsylvania vote, in which polls show Clinton with a comfortable lead over Obama, is key to the former first lady's bid to whittle down her opponent's overall lead in popular votes, delegates and states won.
According to the Associated Press tally of delegates, Obama leads Clinton 1,632-1,500, including the so-called superdelegates, elected officials and party leaders who can vote for whichever candidate they want regardless of primary and caucus outcomes. A total of 2,024 delegates are needed to win the nomination at the party's national convention this summer in Denver.
NBC's national delegate count stands at 1252 for Clinton and 1416 for Obama. NBC’s estimated superdelegate count stands at 255 for Clinton and 222 for Obama.
[There are differences in how news organization count delegates, how they award superdelegates, how they account for states that have held caucuses but have not yet chosen their delegates, and how they project the apportionment of delegates within Congressional districts where the vote was close. The Associated Press and NBC news conduct separate delegate counts.]
But Obama turned his attention to McCain as if victory in the increasingly bitter nomination race against Clinton were a foregone conclusion.
"He's on a biography tour right now," Obama said of McCain. "Most of us know his biography, and it's worthy of our admiration. My argument with John McCain is not with his biography, it's with his policies."
McCain has opened a drive in recent days to define himself as a candidate with an impeccable military pedigree and experience in national security issues absent in either Clinton or Obama.
For his part, Obama has argued that a McCain victory would be another four years of President George W. Bush on economic and military policies.
"Senator McCain has been saying I don't understand national security, but he's the one who wants to keep tens of thousands of United States troops in Iraq for as long as 100 years," Obama said.
McCain has said the U.S. could end up having a long-term military presence in Iraq, similar to the more than 50-year presence of U.S. soldiers in Germany and South Korea.
"One hundred years in a country that had nothing to do with 9/11 may make sense to George Bush and John McCain but it is the wrong thing to do," Obama said, drawing applause at the town-hall session.
McCain spokesman Tucker Bounds said Obama's remarks showed his "complete lack of preparedness to be commander in chief."
"His attempt to paint McCain's position as something else is nothing but the disingenuous, old-style politics that he claims to reject," Bounds said.
Obama latched onto the same theme, promising to create jobs by using $60 billion he said would be saved by ending the Iraq war.
URL: http://www.msnbc.msn.com/id/23916757/
Turning investments into jobs. Hillary's Rebuild America plan and National Infrastructure will help create 3 million new jobs over the next decade. [Calculation based in part on a Federal Highway Administration study by Thomas F. Keane, "The Economic Importance of the National Highway System," adjusted for inflation.] These will be high-wage jobs with good benefits, including: general construction; engineering, design, architecture, and other specialty work; manufacturing and supply of building materials; and research, development, and production of new green infrastructure technologies.
Implement a trade "timeout" to formulate a genuinely pro-worker and pro-American trade policy.
Obama will strengthen the ability of workers to organize unions. He will fight for passage of the Employee Free Choice Act. Obama will ensure that his labor appointees support workers' rights and will work to ban the permanent replacement of striking workers. Obama will also increase the minimum wage and index it to inflation to ensure it rises every year.