Speaking on the ABC News program "This Week with George Stephanopoulos," Obama said middle-class tax relief was his "priority." He said he might put off allowing President George W. Bush's tax cuts for wealthy Americans to expire because such a move might hurt the economy.

"The economy is weak right now," he said. "The news with Freddie Mac (NYSE:FRE) and Fannie Mae (NYSE:FNM), I think, along with the unemployment numbers indicates that we're fragile.

"I want to accelerate those (middle-class) tax cuts through a second stimulus package ... and then we're going to have to re-evaluate at the beginning of the year to see what kind of hole we're in" before deciding on any upper-class tax increases.

Obama said he believed the presidential campaign should not be reduced to a "resume contest."

After noting he served on the Senate Foreign Relations Committee, headed by running-mate Joe Biden of Delaware, the Illinois senator said he would "be happy to have a substantive debate with John McCain about foreign policy."

"This whole resume contest that's been going back and forth is not what the American people are looking for," he said.