For Barack Obama, it is an ember that he has doused time and again, only to see it flicker anew: links to Islam fanned by false rumors, innuendo and association.

The Democratic presidential front-runner and his campaign reacted strongly this week when a photo of him in Kenyan tribal garb began spreading on the Internet.

And the praise he received Sunday from Minister Louis Farrakhan, leader of the black Muslim group Nation of Islam, prompted pointed questions during Tuesday night's presidential debate and in a private meeting over the weekend with Jewish leaders in Cleveland, Ohio.

During the debate, Obama repeated his denunciation of Farrakhan's views, which have included numerous anti-Semitic comments. And, after being pressed, he rejected Farrakhan's support in the presidential race.

The Democratic candidate says repeatedly that he is a Christian who took the oath of office on a family Bible. Yet on the Internet and on talk radio, and in a campaign introduction for Republican candidate John McCain this week, he often is depicted, falsely, as a Muslim with shadowy ties and his middle name, Hussein, is emphasized.

"If anyone is still puzzled about the facts, in fact I have never been a Muslim," he told the Jewish leaders in Cleveland, according to a transcript of the private session.

The photo of Obama wearing Kenyan tribal raiment, taken by an Associated Press photographer during his 2006 visit to the country where his father was born, resurfaced on the Internet amid unsubstantiated claims that it was being circulated by members of Hillary Rodham Clinton's campaign. Clinton and her aides said they had nothing to do with it. The Obama campaign accused them of shameful, offensive fear-mongering.

On Tuesday McCain denounced the introduction he got in Cincinnati that criticized Obama in vivid terms. Talk show host Bill Cunningham referred to Obama three times as Barack Hussein Obama and called him a hack, Chicago-style politician during Cunningham's introduction of McCain.

The Obama campaign is closely attuned to the rumors and insinuations. Information on Obama's Christian faith is prominently available on the Know the facts page of his Web site. The campaign has distributed flyers to churches in states with presidential contests. It encourages supporters to flag any attack that may make its way into cyberspace.

"Our campaign is vigilant in quickly responding to any information about Senator Obama that surfaces, be it on the Internet, in the media or from our opponents," spokesman Bill Burton said Wednesday.

"If there is confusion - and opportunity for political mischief - it derives at least in part from Obama's rich cultural background. His mother was a white woman from Kansas, his father was Kenyan, and he spent part of his childhood in Indonesia, a largely Muslim country.

"My grandfather, who was Kenyan, converted to Christianity, then converted to Islam," Obama said Sunday. "My father never practiced; he was basically agnostic. So, other than my name and the fact that I lived in a populous Muslim country for four years when I was a child, I have very little connection to the Islamic religion."

Obama has become careful in denouncing the links, lately noting that some rumors about him also have been insulting to Muslims. Jim Zogby, founder and president of the Arab American Institute, said many Arab Americans are drawn to Obama because of his cultural background.

"It is clear he wants to have a broader relationship with the Muslim world," Zogby said. "He has a biography that connects him to the Muslim world."

Obama, though in the presidential limelight now for more than a year, is still introducing himself to voters. An AP-Yahoo poll in January asked people to volunteer the first few words that came to mind about each of the candidates, and 4 percent of the respondents, unprompted, mentioned the word Muslim when describing Obama.

Some of the rumors and allegations about Obama clearly are not true yet still spread, often anonymously:

-A debunked chain e-mail circulating widely on the Internet suggests he is hiding his Islamic roots. It says he was sworn into the Senate on the Quran and turns his back on the flag during the Pledge of Allegiance.

He took his Senate oath with his hand on a family Bible, and he says, "Whenever I'm in the United States Senate, I pledge allegiance to the flag of the United States of America. In fact, no candidate could survive if he publicly spurned the pledge."

-Another false report says he attended a Muslim madrassa school as a child in Jakarta. Obama was born in Hawaii and moved to Indonesia when he was 6 to live with his mother and stepfather. He returned to Hawaii when he was 10 to live with his maternal grandparents.

Interviews last year by The Associated Press at the Catholic elementary school in Jakarta found that it is a public and secular institution and has been open to students of all faiths since before Obama attended in the late 1960s. Said vice principal Akmad Solichin: "Yes, most of our students are Muslim, but there are Christians as well. Everyone's welcome here."

-Obama also has faced questions about his pastor at Trinity United Church of Christ in Chicago, where he has been a member for 20 years. Trinity calls itself Unashamedly Black and Unapologetically Christian. But it accepts nonblack congregants. The United Church of Christ's president and general minister, the Rev. John H. Thomas, was quoted in a church publication as pointing out that the Rev. Jane Fisler-Hoffman, Illinois Conference Minister, who is white, has been a member of the congregation for years.

-Obama has been asked about Farrakhan's words of praise and Farrakhan's receipt of an award from Trumpet Newsmagazine, a Trinity church publication last month. Obama told Jewish leaders Sunday: "An award was given to Farrakhan for his work on behalf of ex-offenders completely unrelated to his controversial statements. And I believe that was a mistake and showed a lack of sensitivity to the Jewish community, and I said so."

Farrakhan did not endorse Obama but said Sunday: "This young man is the hope of the entire world that America will change and be made better."

Asked Tuesday night whether he would accept support from Farrakhan, Obama said: "I live in Chicago. He lives in Chicago. I've been very clear, in terms of me believing that what he has said is reprehensible and inappropriate. And I have consistently distanced myself from him."

Following an exchange with Clinton, he then added: "There's no formal offer of help from Minister Farrakhan that would involve me rejecting it. But if the word 'reject' Senator Clinton feels is stronger than the word 'denounce,' then I'm happy to concede the point, and I would reject and denounce."