"The people who say this haven't apparently been listening to me," the likely Democratic presidential nominee said in response to a question at a town-hall style event.
Obama blamed criticism from "my friends on the left" and "some of the media" in part on cynicism that ascribes political motives for every move candidates make. "You're not going to agree with me on 100 percent of what I think, but don't assume that if I don't agree with you on something that it must be because I'm doing that politically," he said. "I may just disagree with you."
The Illinois senator was responding to a question from a self-described "reformed Republican" who said he worked for Democrat Bobby Kennedy four decades ago and thanked Obama for restoring "that faith."
"You had an interesting week of being accused of flip-flopping, which is mostly nonsense," the man said. He then asked Obama to restate his Iraq position, and Obama used the opportunity to dispel the idea he had generally changed his stances.
Since wrapping up the Democratic nomination last month, Obama has voiced positions that break with the Democratic Party's left and seem to shade his own past positions on a range of subjects. He's drawn criticism from some liberal Democrats who question his loyalty and from Republicans who accuse him of flip-flopping.
His remarks aside, Obama is clearly competing for the center of the electorate. Originally best known as an anti-Iraq war candidate, his general election commercials appear nonpartisan and make an obvious play for voters across the political spectrum by focusing on family values and patriotism as well as "welfare to work" and lower taxes.
Over the past few weeks, he angered liberals by supporting compromise electronic surveillance rules for the government's wiretapping program even though the bill provided immunity that he opposed last year for telecommunications companies that conducted warrantless eavesdropping. When the Supreme Court overturned the District of Columbia's gun ban, he said he favors both an individual's right to bear firearms and a government's right to regulate them.
And, he broke with death penalty opponents when he disagreed with the Supreme Court's decision outlawing executions of people who rape children.
On Iraq, he has gone from a boisterous end-the-war call that endeared him to the left flank to more nuanced rhetoric. He has long called for a troop drawdown process that could last 16 months. Last week, he said his upcoming Iraq trip might lead him to refine, but not basically alter, his determination to pull U.S. troops out of combat in Iraq and that the safety of U.S. troops and the stability of Iraq might force him to adjust his timetable. It's a potentially flexible formulation that has troubled liberals even though he's said throughout his candidacy that the nation needs to be careful leaving Iraq.
"I am somebody who is no doubt progressive. I believe in a tax code that we need to make more fair. I believe in universal health care. I believe in making college affordable. I believe in paying our teachers more money. I believe in early childhood education," Obama told his audience here. "I believe in a whole lot of things that make me progressive and squarely in the Democratic camp."
But, he said: "I'm not just somebody who is talking about government as the solution to everything. I also believe in personal responsibility. I also believe in faith."
So, he said when he talks about the idea of recruiting churches and other religious groups to provide community services through faith-based initiatives, as he did last week, "that's not something new. I've been talking about that for years now. I've been organizing with churches for years in the community. So the notion that somehow that's me trying to look more centered, more centrist, is just not true."
He also raised the Supreme Court ruling that upheld the rights of individuals to bear arms and said: "I actually have said that I agree with that for years, even before the ruling came down." He said that doesn't contradict his view that "we've got decent controls over the use of illegal firearms in our community."
And, addressing the questioner's Iraq query, Obama drew cheers when he said: "I opposed this war from the start" and "I have also consistently said that once we were in, we had to be as careful getting out as we were careless getting in."
McCain spokesman Tucker Bounds argued Obama "put politics ahead of principle" on numerous issues and "has proven his rhetoric to be nothing but empty words and broken pledges that are at odds with his left wing partisan record. Barack Obama is wrong: everyone's been listening and still nobody knows what Barack Obama truly believes."
