Arlington County Board Chair Christian Dorsey, who was penalized Thursday for failing to disclose a campaign contribution to the Metro board in a timely manner, filed for bankruptcy last month after falling behind on his mortgage and accruing tens of thousands of dollars in credit card debt.

Dorsey (D), 48, also serves as Northern Virginia’s representative on the Metro board. In a brief interview late Thursday, he attributed his personal financial troubles to a drop in income since he was elected to the five-member Arlington board four years ago.

He said he chose to seek protection under federal bankruptcy law because he was faced with foreclosure on his family’s home in the Columbia Forest neighborhood in South Arlington.

Carrying first and second mortgages and an auto loan, in addition to the credit card debt, he attempted to work out mortgage modification, but his creditors did not agree to it. His Chapter 13 petition was filed Oct. 16 in the U.S. Bankruptcy Court for the Eastern District of Virginia.

“This is the responsible way to handle it,” said Dorsey, who won a second term on the all-Democratic Arlington board Tuesday after facing no primary opponent and only nominal opposition in the general election. “I’m following . . . the process. I would certainly love to be in a position to pay it off. But I made a choice to do public service, and that sacrifice means my income dropped.”

The Metro board on Thursday stripped Dorsey of the chairmanship of its finance committee after learning he had waited more than four months to disclose a $10,000 campaign contribution from the transit agency’s largest union. Ethics rules required him to disclose the donation within 10 days.

Dorsey told The Washington Post on Tuesday that the delay was an oversight. At the request of the board’s chairman, Paul Smedberg, he agreed to return the donation from Amalgamated Transit Union Local 689, which represents most of Metro’s workforce and is preparing to square off with management over the planned privatization of some operations of the Silver Line’s Phase 2.

Dorsey raised $38,606 for his reelection campaign this year, and had $1,892 left in his campaign coffers as of Oct. 24. The $10,000 ATU donation represents about 26 percent of his donations.

He had another $10,000 donation, from the International Brotherhood of Electrical Workers. Smedberg said that because Metro does not directly do business with that union, that donation was not a matter of concern for the transit agency.

As chair of the Arlington County Board, Dorsey is being paid $60,662 this year. That job rotates between members annually, and when he relinquishes it in January, he will make the regular member’s wage of $55,147. He also works as a communications and policy consultant, earning $60,000 annually, the bankruptcy petition said.

Before being elected, Dorsey worked as a senior executive at the Economic Policy Institute and as a consultant. He said he earned significantly more then, but he did not specify what his salary was.

Bankruptcy “is embarrassing,” Dorsey said. “I’d rather it not be the case.”

The bankruptcy petition shows Dorsey has mortgage and auto loan debt of $484,807, as well as credit card or unsecured debt of $86,733. He also faces an Internal Revenue Service tax lien of $27,595.

Dorsey told The Post last month that Arlingtonians should vote for him because he has “the fitness to solve Arlington’s biggest issues — [someone who will] make sure we have a real housing plan, who has the capacity to come up with a storm-water management plan that is fiscally responsible and will work.”

On Thursday, he said he did not consider telling voters of his personal financial travails during the campaign because “the public’s interest is to see that I’m able to do the public’s business.”

He received 37,972 votes Tuesday, behind fellow incumbent Katie Cristol, to easily defeat two independent candidates for one of the two seats on the ballot.

Other county board members reached Thursday expressed support for Dorsey and declined to discuss details of the bankruptcy petition.

“What I’ve felt from him is complete integrity,” said board member Matt de Ferranti.

Cristol said: “At this point, based on what I know about it, it affects him and his family. I doubt if it affects his excellent work as an Arlington County Board member.”

Sandy Newton, president of the Arlington County Civic Federation, a nonpartisan collection of neighborhood associations, said she was sad for Dorsey.

“I don’t think it would have made much of a difference in the election anyway,” she said. “I think he’s a capable person. But he’s bouncing a lot of balls in the air.”

Dorsey said the few members of the Arlington County community who know about his financial situation have been supportive and expressed concern for his family. His wife, Rachel Feldman, is a homemaker, according to the petition, and has been dealing with health problems. Dorsey declined to elaborate.

Feldman served as his campaign manager this year and designed his election literature, for which he paid her $8,000, according to his campaign finance disclosure reports.

Their three-bedroom brick home is listed as worth $790,000 on the bankruptcy petition. They bought it for $625,000 on Aug. 14, 2008, county land records say.

This story has been updated to include that Dorsey also received a $10,000 campaign donation from the International Brotherhood of Electrical Workers, but Metro board chair Paul Smedberg said since Metro does not directly do business with that union, that donation is not a matter of concern for the transit agency.