WASHINGTON — The questions come on cable and radio talk shows, and sometimes from skeptical voters at his own rallies. "Hi, Barack. I am a supporter, a believer and a volunteer for you, and I'm trying to convince my mother to be one also," a woman said at a campaign event last week in Kokomo, Ind. "... One of the issues she has heard is that you do not address the flag."

As Sen. Barack Obama tries to secure the Democratic presidential nomination and turn his attention to the presumptive GOP nominee, Sen. John McCain — a war hero who survived more than five years in enemy captivity — he is facing a crucial test of one of his driving themes: redefining what it means to be a patriot.

After watching past Democratic candidates wither under Republican attacks, Obama has sought throughout his campaign to present his own definition of patriotism, with a call for uniting the country and restoring its values that is, in its way, as redolent with gauzy American exceptionalism as the "shining city upon a hill" of Ronald Reagan.

In forceful tones, he has warned against using the Sept. 11 attacks to "scare up votes instead of a way to bring the country together," condemned the "politics of fear," and demanded an end to the "mind-set that got us into war" in Iraq. When asked in October why he does not wear an American-flag pin on his lapel, he took the question head-on, saying he had worn one after the terrorist attacks but had stopped because it "became a substitute for ... true patriotism, which is speaking out on issues that are of importance to our national security."

Last week, it became more apparent just how much Obama has riding on the bet that a majority of Americans are prepared to define love of country the same way. His former longtime pastor, the Rev. Jeremiah Wright Jr., resurfaced with new fiery commentary on the nation, prompting Obama to break with him a day later.

Republicans and conservative commentators added the episode to their evidence portraying Obama as out of the mainstream — his association with a former member of the Weather Underground; wife Michelle's declaration that "for the first time in my adult lifetime, I am really proud of my country" because of her husband's electoral success; his remarks about "bitter" small-town voters; and false rumors that he does not pledge allegiance to the flag, sparked by a photograph showing him singing the national anthem at an Iowa fair without his hand over his heart.

Adding to Obama's challenge is the Republicans' selection of McCain, who, with his ever-present Navy cap, military lineage and loyal following of fellow veterans, exudes traditional notions of patriotism. A McCain-Obama race would present a contrast between a battle-scarred former fighter pilot who believes in seeing through the war in Iraq and a man 25 years his junior whose half-Kenyan roots symbolize Americans' increasingly diverse origins, who did not serve in the military, and who argues that the country's values have been threatened, not upheld, by the Iraq war.

LESSER CONTRASTS

Republicans have in the past capitalized on lesser contrasts, painting Michael Dukakis and Al Gore as disconnected from real America, and even questioning the principles of decorated war veterans such as George McGovern and John Kerry.

Obama "has a willingness to confront a theme that has traditionally been a real liability for Democrats," said Jim Jordan, who ran the early part of John Kerry's 2004 campaign. "He talks about love of country in a more convincing and natural way than most Democrats do, than we've seen in a long time."

That has not stopped the attacks from coming. Karl Rove, President Bush's former chief strategist, recently chided Obama for his flag-pin decision, accusing him of declaring that if you do wear one, "you're not a true patriot." Republican pollster Whit Ayres called Obama "George McGovern without the military experience." Setting up a contrast, a recent McCain ad declared the Republican candidate "the American president America has been waiting for."

Pressed by Clinton at the Philadelphia debate, Obama said he expects "all kinds of attacks" but has confidence that he can "talk to the American people honestly and directly about what I believe in." But he appeared flummoxed, as though unsure of how to handle insinuations about his patriotism from a fellow Democrat against whom he is more constrained in returning fire. And the combination of hits has taken a toll. A poll released last week by the Pew Research Center showed that 61 percent of voters viewed Obama as patriotic, compared with 76 percent for Clinton and 90 percent for McCain.

At the same time, Obama has consistently scored better than Clinton on most other personal traits, pointing to another reason he may able to weather attacks on his patriotism more successfully than past Democrats — his congenial nature and skills as a communicator. But still, there may be limits, said Pew Director Andrew Kohut. "He has an ability to take a really bad situation and handle it," Kohut said. "The question becomes how many more he can handle."

Since the controversies over his wife's comments and the Wright remarks, Obama has imbued his speeches with an even stronger patriotic touch, including frequent mentions of his grandparents' contributions during World War II.

"You want to know about my patriotism?" Obama said last week in Chapel Hill, N.C. "My patriotism is rooted in the fact that my story, Michelle's story, is not possible anywhere else on Earth. That the American dream, despite this country's imperfections, has always been there. ... That there are ladders of opportunity that all of us can climb. That we're all created equal. That we're all endowed with certain inalienable rights — life, liberty, the pursuit of happiness. ... That we're willing to shed blood for those liberties, we're willing to speak out for those liberties. ... That we can make this country more just and more equal and more prosperous and more unified. That's why I love this country. That's why you love this country."

But David Axelrod, Obama's chief strategist, said the candidate's patriotism has been at the center of his appeal since his 2004 Democratic National Convention speech, which Axelrod said laid out Obama's vision that "we have a stake in each other as Americans, that we have a great legacy that we have to rally around." Axelrod said the message would stand up under assault. "A campaign for president of the United States reveals who you are, and who he is is someone who has experienced the greatness of America," he said. "I have ultimate faith in the American people to judge him and others for who they are."

MIXED LANDSCAPE

Interviews with voters show that Obama faces a mixed landscape. In Missoula, Mont., Tim Ellis, a retired teacher, said attacks on Obama's patriotism will not fly. "I have more confidence in the American people than that," he said. "This guy is as solid an American as you'll find. People will be wise enough to see it for what it is."

But in southwestern Pennsylvania, Cindy Valcheck, a customer service worker and Democrat, said she would not vote for Obama in the fall because he "doesn't even pledge to the flag."

In Kokomo, Obama leaped on the flag question. He again explained his lapel decision, saying he was put off by politicians who wore the flag pin but voted against funding for veterans, and described the national-anthem moment in Iowa, noting in a joking aside that many sports fans don't put their hands over their hearts during the anthem at ballgames.

"This is a phony issue. ... I've been saying the pledge since I was, what, 4?" he said to applause. "So I make this comment and suddenly a bunch of these TV commentators and bloggers say, 'Obama is disrespecting people who wear flag pins.' Well, that's just not true. Another way of saying it is: It's a lie. So ... don't listen to them. Look at what I do and what I say and my commitment to making this a stronger country. I get pretty fed up with people questioning my patriotism, especially a bunch of folks who have instituted policies that have made America weaker. I am happy to have that debate with them, any place, any time. All right?"