Rep. Jim Moran calls political colleagues from his Capitol Hill office Wednesday, the morning he announced his decision not to seek reelection to Congress. (Melina Mara/The Washington Post)

U.S. Rep. James P. Moran announced Wednesday that he will retire after more than two outspoken and controversial decades in Congress, throwing open a heavily Democratic seat in Northern Virginia.

Moran, a big, pugnacious politician raised in a large Irish Catholic family near Boston, has represented the affluent, ­liberal-leaning suburbs hugging the Potomac River since his election in 1990 and has been a fixture in Alexandria politics for 35 years. The Democrat’s 8th District seat has long been safe, and he had no declared primary or general-election opponent before Wednesday. That, Moran said in an interview, is precisely why now is the “ideal time” to retire.

“Knowing myself, if there was a challenger, I know I wouldn’t be retiring,” Moran said. “I could never let anyone suggest that I was backing down from a challenge. . . . I want to go out on a high note.”

He continued: “This is the time to leave, when you’re in a position when you have no regrets, or the least regrets. I don’t have anything that I need to overcome or prove to myself, from a professional standpoint.”

Moran, 68, is the second veteran Northern Virginia lawmaker to announce in recent months that he will leave Congress. Rep. Frank R. Wolf (R), in the neighboring 10th District, will also end his political career after this term.

Moran is the 15th member of Congress and sixth Democrat to retire in this cycle. Unlike some in his party, he has had little reason to fear reelection or the challenge of defending his support for the Affordable Care Act. But Moran did acknowledge that he was tired of serving in the House minority.

“That’s part of it. . . . There is some frustration,” he said.

As a long-serving member of the House Appropriations Committee, Moran said the current environment on the Hill, marked by partisan dysfunction and an emphasis on fiscal discipline, makes it difficult to accomplish as much as he wished.

“We all recognize that there’s going to be little to do in terms of new initiatives, especially anything bold . . . over the next few years,” he said.

Moran’s district, which includes Arlington County, Alexandria, Falls Church and a portion of Fairfax County, is overwhelmingly Democratic, delivering 68 percent of the vote to President Obama in 2012. Moran said he expected a “crowded primary,” particularly given that the seat has not been vacant in more than two decades and that the primary winner is almost certain to prevail in November. Republicans are less likely to field a top-tier candidate, given the district’s makeup.

Potential Democratic candidates for the seat include a long list of current and former local and state officials from Alexandria, Arlington and Fairfax. ­Moran’s brother, former state delegate and 2009 gubernatorial contender Brian J. Moran, is not expected to run; he has been nominated to serve as secretary of public safety in Virginia Gov. Terry McAuliffe’s Cabinet.

On the Republican side, former congressional aide and current Aerospace Industries Association executive Micah Edmond filed paperwork Wednesday to run for Moran’s seat. Edmond said he is running “because our country is facing a budget crisis that is undermining our national security, our economic security and our ability to invest in the future.”

Moran was born in Buffalo but grew up in Massachusetts, and he still bears the accent to prove it. He relocated to the Washington area and immersed himself in Northern Virginia politics, joining the Alexandria City Council in 1979. He went on to serve as mayor of Alexandria and then won election to Congress.

In a statement from the White House, Obama said that “because of Jim’s leadership, our brave service members and veterans are better protected, our civil service is stronger, and our air and water are cleaner and safer.”

McAuliffe (D) said that Moran was “a voice for so many who are often left on the margins of our society,” and Rep. Rob Wittman (R-Va.) praised Moran for “fighting for our hardworking federal employees.”

Moran is a founder of the New Democrat Coalition, which promoted business-friendly policies within the party. He has spent much of his time in Congress focused on appropriations, developing close relationships with the defense industry and the federal contractors that heavily populate his district.

His record has been more liberal on social issues, and he has been a vocal advocate for environmental causes and increased restrictions on guns.

He has also frequently courted controversy.

In 1999, Moran drew attention for taking personal loans from a friend who was a drug-company lobbyist. He got another loan three years later from the co-founder of America Online. The Washington Post reported in 2002 that Moran received favorable terms on a home-refinancing package from MBNA as he backed a bankruptcy reform bill supported by the credit card industry. Moran was not charged with wrongdoing in those instances.

The congressman also has made controversial statements about the Middle East. In 2003, he told attendees at an antiwar forum, “If it were not for the strong support of the Jewish community for this war with Iraq, we would not be doing this.” He also said that Jewish leaders were “influential enough” that they could change the course of U.S. policy.

Moran eventually apologized for those remarks, which helped fuel his strongest primary challenge: the 2004 bid by lawyer Andrew Rosenberg. Moran won by 59 percent to 41 percent.

In 1995, Moran got in a shoving match on the House floor with then-Rep. Randy “Duke” Cunningham (R-Calif.) during an argument over Cunningham’s allegation that Moran had “turned his back” on Operation Desert Storm. (Moran voted against authorizing force in the Persian Gulf War in 1991.)

In 1999, his second wife — Moran has divorced three times — called police after a domestic dispute, although no charges were filed. The next year, Moran got into a heated argument with an 8-year-old boy whom Moran accused of trying to steal his car keys; the incident made national news.

Moran has also had personal financial troubles. A former stockbroker, Moran lost roughly $120,000 from trades and bad investments in the mid-1990s and went into significant debt. During their divorce, his second wife accused him in court papers of “wasting the family assets on his stock market gambling.”

Moran was an active trader again in the mid-2000s, with assets owned by his wealthy third wife. After their 2010 separation and eventual divorce, his financial situation changed significantly. His most recent financial disclosure report, covering 2012, shows him to be one of the least wealthy members of Congress, with no assets other than a money-market account worth $15,000 or less.

Moran said Wednesday that he believed he “may be able to accomplish more outside” Congress than inside, when it comes to causes he cares about. He declined to say what he plans to do next, although as a longtime appropriator he could presumably command a large salary in the private sector.

“Ethically, it’s inappropriate and wrong to try and take care of yourself while you’re still serving,” he said.

Michael Laris, Patricia Sullivan and Laura Vozzella contributed to this report.