It was not the victory James P. Moran Jr. had hoped for.

Over seven terms, the Democratic congressman from Northern Virginia has denied his seat to Republican opponents by drawing 60 percent of the vote and more.

But he said yesterday he was disappointed that his constituents did not give him more than 59 percent against a little-known opponent Tuesday in his first primary fight.

"It's up to me to work all the harder to reach out to those people who did not vote for me and understand why they didn't and how I can bridge their perception of me," Moran, 59, said in a break from a committee meeting on a homeland security spending bill on Capitol Hill.

As he reflected on his primary against lawyer Andrew M. Rosenberg, Republican Lisa Marie Cheney kicked off her campaign to unseat Moran in November's general election. An activist from Alexandria who runs a consulting firm specializing in national security issues, Cheney, 39, began introducing herself to voters from Rosslyn to Reston in the heavily Democratic 8th District.

"The margins show Congressman Moran is very vulnerable," said Cheney, whose husband is distantly related to Vice President Cheney. "The Democrats are not energized; they're divided and they're not enthused about their candidate, and that's going to help me."

Moran acknowledged that the primary, in the absence of big differences with Rosenberg on issues, "became a referendum on me and my service to the community."

His advisers said his victory margin was eroded by at least 5 percentage points by an allegation days before the primary from Moran's former pollster, Alan Secrest, that Moran made an anti-Semitic remark during a private campaign meeting in March.

Secrest has not been specific about what Moran said, and Moran and two other advisers at the meeting said he made no such comment.

But Secrest's charge became another chapter in a saga of ethical and political controversies involving the congressman. In March 2003, Moran angered American Jewish leaders when he told an antiwar forum that the Jewish community was pushing the country into war with Iraq.

"As people get away from [the Secrest allegation], they will realize that Jim deserves another term because he's got an exemplary record," said state Sen. Richard L. Saslaw (D-Fairfax), who wrote voters a letter on Moran's behalf last weekend.

Moran found his strongest support Tuesday in his home base of Alexandria but lost some precincts in the Crystal City, Clarendon and Courthouse areas of Arlington County.

Those are neighborhoods with large concentrations of high-rise buildings where newer, relatively transient residents might be unfamiliar with Moran's long political career, his campaign advisers said. He also lost in Reston, a more established, politically active area that he has represented only recently, since redistricting based on the 2000 Census pushed the 8th District farther into Fairfax County. Rosenberg campaigned hard in both areas.

Elected Democrats in Reston stayed neutral in the race, making Moran more vulnerable there, observers said.

"I knew it would be a difficult race," said Fairfax Supervisor Catherine M. Hudgins (D-Hunter Mill), whose district includes Reston. "I have constituents on all sides of this. It may have been that in a newer area to the district, there was less solidified support" for Moran.

Moran said he was heartened by his strength in low-income communities inside the Capital Beltway, where his support for underdog causes has resulted in affordable housing, homeless shelters and programs to help teenage mothers.

The congressman said he will continue his back-to-basics campaign, relying on town hall-style meetings and small gatherings of supporters in living rooms rather than polls, television advertising and extensive mailings.

But ultimately, Moran said, "we need to reassess whether we can run as grass-roots-oriented a campaign" against Cheney. That contest, with the presidential race between President Bush and Sen. John F. Kerry (D-Mass.) as a backdrop, might require a more conventional effort for an incumbent, he said.

Cheney called herself a fiscal conservative and social moderate who opposes abortion rights but does not support the president's push for an amendment to the U.S. Constitution to ban gay marriage. Her campaign will focus on homeland and national security issues. "What has our member of Congress done to make us feel secure and safe in our district?" she said.

Moran said he "can't imagine" that Cheney will make much headway with voters on the issues. "That's one of the things I can take legitimate credit for, steering billions of defense and homeland security dollars to Northern Virginia," he said.

Cheney said she will need to raise $1.8 million for her campaign. With about $400,000 in the bank after the primary, Moran said, he does not expect he will need to raise as much as that to hold on to his seat.