A longtime adviser to Rep. James P. Moran Jr. has lodged about the most damaging allegation that could be made about the congressman from Northern Virginia at this point in his reelection campaign: that he heard him make an anti-Semitic remark.

Last night, the seven-term congressman said he is "stupefied" at the allegation by his former campaign strategist and pollster, Alan M. Secrest, and called it a "flat-out lie."

The dispute marks another unpredictable turn in the career of the Washington region's most talked-about congressman. In Tuesday's 8th District Democratic primary, Moran, 59, faces a challenge from Andrew M. Rosenberg, an Alexandria lawyer who has made an issue of the incumbent's personal conduct and ethics, in particular a remark he made last year that angered American Jewish leaders and Democratic leaders.

Secrest, a prominent Alexandria-based pollster who has run 300 successful campaigns for Democratic members of Congress, said Moran made an anti-Semitic reference to the staff of a national Democratic campaign committee during a private meeting with advisers several weeks ago.

"The remark I'm referring to was anti-Semitic in nature," he said in an interview yesterday. He would not say what the remark was or explain why he would not say.

Secrest severed his 20-year relationship with Moran in a scathing letter dated May 25. He said in the letter that he had anguished over Moran's "increasingly erratic behavior."

Secrest wrote: "The final straw, for me, were your offensive remarks in a recent internal campaign meeting, remarks you have refused to clarify, amend, or apologize (even internally) for." He also cited a string of "maliciously inappropriate characterizations of others."

He added: "At some point, Jim, it isn't enough to be chagrined, embarrassed, and full of self-pity. You have to commit to making a change."

Secrest's resignation was first reported yesterday by Roll Call, a Capitol Hill newspaper.

Moran has been dogged in recent years by financial, ethical and personal controversies. He has been on the defensive for accepting a $25,000 loan from a drug company lobbyist whose bill he supported and a $447,000 debt-consolidation mortgage package he received from a credit card giant that sought legislation he co-sponsored.

Last year, an uproar developed over comments he made at a peace vigil in Reston that American Jews were pushing the country toward war with Iraq.

The meeting that Secrest refers to in his letter took place at the McLean home of Moran's fiancee to discuss the strategy for the final stretch of Moran's primary fight against Rosenberg. Also present were longtime Moran advisers Mame Reiley, director of Gov. Mark R. Warner's political action committee, and Joe Trippi, a political consultant who advised former Vermont governor Howard Dean's presidential campaign.

Moran recalled that Secrest was pressing him to conduct a poll. If the results were favorable, the poll could be used to draw donations from the Democratic Congressional Campaign Committee. Moran said he was against the idea. "I said I wasn't going to ask them to endorse me or give me money," Moran said, "because there are a lot of young kids [on the staff] there that don't know me."

He said he does not know whether the committee's staff has Jewish members. "It never occurred to me what their religion is."

Reiley and Trippi recalled that Moran and Secrest exchanged angry words and raised their voices in a dispute over money and polling.

Reiley said Secrest was unhappy that the campaign was not fulfilling the terms of a contract.

"I have never heard Jim Moran say an anti-Semitic remark, nor would I permit anyone ever saying an anti-Semitic remark in my presence," she said.

Asked whether Moran made an anti-Semitic remark, Trippi said, "Not that I heard. I don't believe that." Trippi said Moran and Secrest exchanged "some fairly harsh words" in an argument over money and the poll.

"The only thing I heard in there was, 'I think we should poll,' and he [Moran] made some comment that Alan wanted more money, and Alan got upset, you know, kind of offended by that," Trippi said.

Moran said of Secrest: "He's a vendor. I felt he should have had a different plan for how to run this particular campaign."

While Secrest was pushing a costly strategy that involved expensive polls and media advertising and focused on defeating President Bush, Moran and campaign director Dan Lucas chose a cheaper, more grass-roots approach, Moran said.

The two had argued over money, but they settled the dispute, Moran said.

Secrest said any campaign dispute was irrelevant to Moran's remark and Moran's refusal to apologize or acknowledge his conduct. "It did add to the discomfort, the fact that it was that kind of a campaign, but that must happen a dozen times a cycle. . . . It's not unusual to have debates over campaign philosophies or approaches, particularly with Jim Moran. We've been having disagreements as a team over 20 years."

Rosenberg, 36, said in an interview: "Alan Secrest is a nationally renowned and respected pollster, with an impeccable reputation. For him to take a stand like this, especially only one week in front of an election, speaks volumes about Congressman Moran and the things he must have said."

Federal Elections Commission records compiled by Political Money Line show Moran's campaign paid Secrest's firm $31,350 for polling services for the 2002 election and $38,300 for the current election cycle.

The last payment of $8,000 was made on May 3.

Researcher Lucy Shackelford contributed to this report.