ORLANDO -- Barack Obama on Tuesday said John McCain was wrong to support the invasion of Iraq and criticized his Republican rival for questioning his patriotism and judgment on issues of national security.

"He said that I have changed my position on Iraq when I have not," Obama told the Veterans of Foreign Wars convention in Orlando, Fla., one day after McCain addressed the group. "He said that I am for a path of 'retreat and failure.' And he declared, 'Behind all of these claims and positions by Senator Obama lies the ambition to be president' - suggesting, as he has so many times, that I put personal ambition before my country."

"That is John McCain's prerogative," the presumptive Democratic presidential nominee said. "He can run that kind of campaign...But I believe the American people are better than that. I believe that this defining moment demands something more of us."

Obama reaffirmed his early opposition to the U.S. invasion of Iraq and said the so-called "surge" strategy of sending 30,000 additional troops to Iraq last year had not produced the political reconciliation necessary to achieve lasting peace in the country. McCain supported the Iraq invasion and was an early champion of the surge.

"These are the judgments I've made and the policies that we have to debate, because we do have differences in this election," Obama said.

McCain -- a Vietnam war veteran and member of the Senate Armed Services Committee -- addressed the same group Monday and said Obama had sought to "legislate failure" in the Iraq conflict. McCain also suggested that Obama had placed political ambition before victory in Iraq -- a claim the Illinois senator rejected.

"Instead of just offering policy answers, he turned to a typical laundry list of political attacks," Obama said.

McCain campaign spokesman Tucker Bounds was quick to respond to Obama's remarks Tuesday, saying, "Unlike Barack Obama, John McCain doesn't have to compensate for a lack of credibility on the international stage with inflammatory and public threats against American allies. The American people know that John McCain will hunt down terrorists wherever they are, and have a choice between strength and experience versus Barack Obama's rhetoric and theatrics."

FOX News' Bonney Kapp and Mosheh Oinounou and The Associated Press contributed to this report.