Sen. Barack Obama defended his patriotism yesterday as he sought to inoculate himself from attacks for his lack of military service, complex biography and past incidents that have generated questions about his American values.

"It's worth considering the meaning of patriotism because the question of who is — or is not — a patriot all too often poisons our political debates," the presumptive Democratic presidential nominee said in a speech at the Truman Memorial Building in Independence, Mo.

"I have always taken my deep and abiding love for this country as a given," he said. "Yet, at certain times over the last 16 months, I've found, for the first time, my patriotism challenged — at times as a result of my own carelessness, more often as a result of the desire by some to score political points and raise fears and doubts about who I am and what I stand for."

Obama, who has been the subject of false Internet rumors about his background and questioned about his willingness to wear a U.S. flag pin on his lapel, is expected to speak on the patriotism theme through this week's Independence Day holiday.

In his speech, Obama pledged to "never question the patriotism of others in this campaign" and said he would "not stand idly by when I hear others question mine."

The Illinois Democrat also spoke by phone for about 20 minutes with former President Bill Clinton, who was frequently critical of him during the heated primary season. It was their first conversation since Obama defeated Sen. Hillary Clinton, the former first lady, to secure the party's nomination.

"He has always believed that Bill Clinton is one of this nation's great leaders and most brilliant minds, and looks forward to seeing him on the campaign trail and receiving his counsel in the months to come," Obama spokesman Bill Burton said in a statement.

As Obama offered his definition of patriotism, he detailed several life experiences.

"One of my earliest memories is of sitting on my grandfather's shoulders and watching the astronauts come to shore in Hawai'i," he said. "I remember the cheers and small flags that people waved, and my grandfather explaining how we Americans could do anything we set our minds to do. That's my idea of America."

Obama used that last line with several more examples, including his grandfather's pride in serving in World War II and listening to his mother talk to him as a child about the Declaration of Independence and Constitution.

As he grew older, Obama said he gained a greater awareness of the "nation's imperfections." But he also came to believe that what makes the United States remarkable is its belief that it can constantly become better.

MCCAIN DEFENDED

Also yesterday, Obama rejected a retired general's suggestion that Republican John McCain's military experience didn't necessarily qualify him to be president, as GOP surrogates lined up to label the remarks indecent and disrespectful.

A day after retired Army Gen. Wesley Clark, now an Obama supporter, discussed McCain's experience as a Navy pilot and prisoner of war in Vietnam on a Sunday talk show, his remarks set off the pattern that has become familiar from innumerable earlier flaps over surrogate remarks during the presidential election year: The candidates, Obama and McCain, took the high road while the bare-knuckled language was left to their surrogates.

At a news conference in Harrisburg, Pa., yesterday, McCain himself said of Clark's comment, "That kind of thing is unnecessary" and distracts from real pocketbook issues voters care about.

About the same time, Obama told his audience in Independence that McCain had "endured physical torment in service to our country" and "no one should ever devalue that service, especially for the sake of a political campaign, and that goes for supporters on both sides."

The latest dust-up began on CBS' "Face the Nation." Clark, the former supreme commander of NATO under Bill Clinton, said McCain's military service was not the same as executive experience.

"He has been a voice on the Senate Armed Services Committee and he has traveled all over the world, but he hasn't held executive responsibility," Clark said. "That large squadron in the Navy that he commanded — that wasn't a wartime squadron."

Clark has said as much before, but drew little notice. CBS moderator Bob Schieffer cited Clark's earlier remarks and noted that Obama hadn't had those experiences either nor had he ridden in a fighter plane and been shot down.

"Well, I don't think riding in a fighter plane and getting shot down is a qualification to be president," Clark replied.

Clark stood by his remarks yesterday. He issued a statement commending McCain's military service but insisted that his criticism stood.

The Associated Press contributed to this story.