A Democratic congressional candidate in Minnesota, Keith Ellison, is poised to make history. The attorney and two-term state lawmaker could become the first Muslim ever to serve in Congress, as well as the first African-American to represent his state in Washington.

However, another possibility is that next week Mr. Ellison will become one of the first politicians defeated in a Democratic primary because of hard-hitting posts by conservative bloggers.

“They’ve driven the discussion by their own research and analysis,” a political science professor at Carleton College in Northfield, Minn., Steven Schier, said. “That’s been the real dynamic of the race.”

“The bloggers, they brought out the blowtorches and said, ‘You’re not really asking the tough questions here,'” another political analyst, Lawrence Jacobs of the University of Minnesota, said.

The bulk of the trouble for Mr. Ellison, 43, has come from MinnesotaDemocrats-Exposed.com, a blog run by a local Republican operative, and a national conservative blog, Power Line, which is best known for helping to bring down a CBS News anchor, Dan Rather.

Soon after Mr. Ellison won the endorsement of Minnesota Democrats at a party convention in early May, the blogs began drawing attention to the lawmaker’s background, and in particular his affiliation with a black Muslim group that espouses anti-Semitic views, the Nation of Islam.

The author of Minnesota Democrats Exposed, Michael Brodkorb, posted articles that appeared in the University of Minnesota student newspaper in 1989 and 1990 under the name of Keith Hakim. One piece was a defense of the Nation of Islam’s leader, Louis Farrakhan. The other called for reparations for African-Americans, as well as a new black nation to be created from Arkansas, Alabama, Georgia, Louisiana, and Mississippi.

Mr. Brodkorb said Keith Hakim was a name Mr. Ellison used while a law student at the University of Minnesota. Mr. Ellison later acknowledged to reporters that he wrote the articles.

On May 28, Mr. Ellison sought to tamp down the controversy with a letter to the local Jewish Community Relations Council. “I would like to state for the record that I categorically and unequivocally reject anti-Semitism in any form and from whatever source,” he wrote.

Mr. Ellison said he worked with the Nation of Islam and helped promote its so-called Million Man March in 1995 out of concerns about a crisis involving African-American men. However, he conceded that he “did not adequately scrutinize the positions and statements” of the black Muslim group’s leaders, such as Mr. Farrakhan. “They were and are anti-Semitic, and I should have come to that conclusion earlier than I did. I regret that I didn’t. But at no time did I ever share their hateful views or repeat or approve of their hateful statements directed at Jews, gays, or any other group.”

The head of the group that received Mr. Ellison’s apology, Stephen Silberfarb, said Jewish reaction to the letter was mixed. “There were some people who accepted it, some people for whom it was a relationship that’s unforgivable, and there were some for whom they just didn’t buy it,” Mr. Silberfarb said.

A Jewish couple among the most prominent liberals in Minneapolis, Samuel and Sylvia Kaplan, met with the lawmaker and discussed his views.

“He explained it in a reasonable way,” Mrs. Kaplan said. “He’d never done anything indicating any kind of personal prejudice.”

“We are quite satisfied that this is a very good guy, a very gifted person,” Mr. Kaplan added.

Since the flap over his ties to the Nation of Islam, Mr. Ellison’s record on Jewish issues has been spotty, local leaders said. He unequivocally condemned Hamas and Hezbollah as terrorist groups, a position that few politically active members of the American Muslim community have been willing to take. However, he recently appeared at a Muslim-organized fund-raiser for his campaign at which a leader of the Council on American-Islamic Relations spoke. Many Jewish leaders view that group as apologists for terrorism.

Still, last week, Mr. Ellison won the endorsement of Minneapolis’s Jewish newspaper, the American Jewish World.

Over the summer, Mr. Ellison was buffeted by a flurry of blog-driven accusations about his failure to pay taxes, suspended driver’s license, and incomplete campaign finance reports.

“This fellow seems to be impaired in his ability to do basic documentation,” Mr. Schier said. “This didn’t come up during the endorsement contest at all, which is a real indictment of the party apparatus.”

“Every allegation that’s been reported on Ellison has been reported in a blog before,” Mr. Brodkorb said. He said the mainstream press fleshed out some claims, helping to establish that the suspended license stemmed from unpaid tickets. Mr. Ellison has had at least 55 parking or traffic tickets, including 17 moving violations, Mr. Brodkorb said.

Thus far, one of the founders of Power Line, Scott Johnson of Minneapolis, has written 20 blog entries about Mr. Ellison. He is particularly concerned about Mr. Ellison’s presence and statements at rallies defending gang members accused of violence against police.

“We don’t get no justice, you don’t get no peace,” Mr. Ellison reportedly said at a 1993 rally on behalf of defendants on trial for the murder of a Minneapolis police officer, Jerome Haaf.

“He seems to have a jones for cop-killers,” Mr. Johnson said of Mr. Ellison.

Many of the bloggers’ posts taunt the Minneapolis Star Tribune for being slow to raise questions about Mr. Ellison’s past.

“I think I’ve eaten their lunch on this story. They’re so paralyzed by political correctness they’ve let us have a field day,” Mr. Johnson said.

A political writer and editor at the Star Tribune, Conrad deFiebre, said the paper “may have gotten some tips from the blogs.”

However, he said there has been no effort to suppress stories about Mr. Ellison. “There was no reluctance on our part and there were no delays,” Mr. deFiebre said.

Mr. Ellison’s campaign did not respond to requests for an interview.

Messrs. Brodkorb and Johnson contend that Mr. Ellison has yet to give full answers to the questions raised by their posts. For instance, the lawmaker told reporters he was never a member of the Nation of Islam, but was affiliated with the group for about 18 months in the mid-1990s. The bloggers claim there is evidence that Mr. Ellison was involved with the organization for nearly a decade.

Some Democrats contend that Mr. Brodkorb is simply a Republican opposition researcher using his blog to release raw information that would be vetted more closely by mainstream press outlets. Others accuse the bloggers of using guilt-by-association tactics to try to hold Mr. Ellison responsible for comments and actions taken by others.

The congressional seat is being vacated by Rep. Martin Sabo, who is retiring. Other Democrats in the race include Mr. Sabo’s chief of staff, Michael Erlandson, a former state senator, Ember Reichgott Junge, and a Minneapolis city council member, Paul Ostrow. A University of Minnesota business professor, Alan Fine, is running as a Republican, but the September 12 Democratic primary is all but certain to anoint the ultimate victor in the liberal and overwhelmingly Democratic 5th District.

At times, the campaign has seemed to focus on which candidate is most staunchly opposed to the war in Iraq. Many voters have accorded that title to Mr. Ellison.

Mr. Jacobs said Mr. Ellison deserves credit for his sheer staying power. “The questions were of the most telling sort: Is he law abiding? Is he anti-Semitic? If he wasn’t able to push back, the campaign could have imploded,” the professor said. “He has survived. That’s a non-trivial accomplishment.”