"We've had a terrific contest between myself and Senator Clinton and the other candidates who were originally involved," Obama told a forum with middle-class voters in the town of Blue Bell outside of Philadelphia.
"Democrats are pretty unified around some ideas," Obama said, citing the desire to provide universal health care and tackle global warming.
PLAYING DOWN EXPECTATIONS
Both camps tried to play down expectations in Pennsylvania, where Clinton's once double-digit lead has dwindled to single digits in many polls as Obama has outspent her heavily.
"I think it's going to be pretty close and we're campaigning hard," Obama said.
Obama told a rally in McKeesport, near Pittsburgh it was it was unfair for the media to question him about his patriotism as happened during an ABC news debate last week when he was asked whether he believed in the American flag and why he did not always wear a flag pin on his lapel.
"It frustrates me that people would even have a question about something like that because they don't ask the same questions of some of the other candidates," he said. "That concerns me."
Obama leads Clinton in delegates to the August convention in Denver, but neither can clinch the nomination without the help of superdelegates - nearly 800 party insiders who are free to support either candidate.
Obama also picked up an endorsement from fiery filmmaker Michael Moore, who made he anti-Bush documentary "Fahrenheit 911."
"What we are witnessing is not just a candidate but a profound, massive public movement for change. My endorsement is more for Obama The Movement than it is for Obama the candidate," Moore wrote in a letter posted on his Web site.
Clinton hopes a big win in Pennsylvania and a strong run through the nine remaining Democratic contests will convince superdelegates she is the candidate who can capture the big states crucial to a November election victory.
Clinton has resisted calls from Obama supporters to pull out of the race and let him focus on the election battle against McCain.
McCain launched a five-day tour of economically struggling areas rarely visited by Republicans. He opened in Selma, Alabama, at a landmark of the U.S. civil rights movement - the bridge where state police attacked more than 500 civil rights demonstrators in 1965 on a day known as "Bloody Sunday."
McCain's trip also will take him to the hard-hit steel town of Youngstown, Ohio, the Appalachia region of Kentucky and hurricane-stricken New Orleans.
