The Metro board is considering penalizing board member Christian Dorsey for waiting more than four months to disclose a $10,000 campaign contribution from the transit agency’s largest union, officials said Tuesday.

Metro’s code of ethics requires such disclosures to be made to the agency within 10 days.

Dorsey (D), who also chairs the Arlington County Board, received the contribution from Amalgamated Transit Union Local 689 on June 21. He disclosed it then to Virginia authorities in accordance with state campaign finance law.

But he waited until Oct. 30 to submit a revised financial disclosure form to Metro, a delay he called “simply an oversight.”

“Once I realized it, I corrected it,” Dorsey said in a telephone interview Tuesday night, hours after the Metro board held a private conference call to discuss the matter.

Dorsey spoke shortly before election returns came in confirming he had easily won reelection to the County Board.

The union donation “was disclosed with my campaign finance filings,” Dorsey said. “It took awhile, which is on me, to amend my [Metro] disclosure,” he said.

Dorsey reaffirmed a previous statement that he will recuse himself from board actions involving the union and added that he will accept any sanctions that the board or Metro ethics officers decide.

That could include giving up his chairmanship of the board’s Finance and Capital Committee, according to officials familiar with the matter, who spoke on the condition of anonymity because the discussions are confidential.

“I will follow whatever guidance ethics officers dictate,” Dor­sey said.

The board has not concluded formally that Dorsey violated ethics rules, but it appeared likely to do so, the officials said. The board was considering asking the Metro inspector general to investigate Dorsey’s actions.

The case is expected to be discussed Thursday at regularly scheduled board committee meetings.

Dorsey’s handling of the union campaign donation creates a new ethics controversy for the board 4½ months after former chairman Jack Evans (D) resigned after an outside law firm found he had committed multiple violations of the board’s ethics code.

Another report on Evans was made public Monday in which a law firm retained by the D.C. Council found Evans repeatedly used his District office on behalf of private clients who paid him hundreds of thousands of dollars without proper disclosure.

Paul Smedberg, who succeeded Evans as the Metro board chairman, believes it’s important to move quickly to address the Dor­sey case, and to do so publicly, in line with reforms to the ethics process adopted after the Evans scandal, according to officials familiar with the Tuesday conference call. Smedberg declined to comment.

Some board members believe Dorsey’s delay in reporting the union donation was an honest mistake and not as serious as Evans’s conduct. They view Dor­sey as a valuable colleague. He was considered a possible candidate to succeed Evans as chair but was not eager for the job because of his responsibilities as Arlington County Board chairman.

“Christian is really an asset. He’s smart,” said one official familiar with the Metro board’s proceedings. The person added that the board needed to treat the matter “very seriously” and in a “transparent process,” partly because it was under extra public scrutiny in the wake of the Evans scandal.

It was not clear whether the board considered it acceptable for a member to accept donations from the union, which represents most of Metro’s workforce. The union negotiates pay and benefits that account for the bulk of the transit agency’s operating budget and is frequently at odds with management over work rules and disciplinary procedures.

Nearly 130 ATU members are on strike at a Metrobus garage in Lorton, in a protest over wages and other issues at the facility operated by a private contractor. The union is seen as flexing its muscles before a bigger battle expected over Metro’s plans to use private contractors to operate phase two of the Silver Line when it is completed.

The Metro board’s ethics code provides that members “may solicit bona fide . . . political contributions,” but with the condition that “it cannot reasonably be inferred that the contribution is offered in an effort to influence the Board Member’s action upon a WMATA matter or offered as a reward for the Board Member’s action upon a WMATA matter.”

The ethics code also says Metro board members have a “duty to avoid conflicts of interest,” and “shall endeavor to . . . avoid compromising independence or impartiality; and avoid any other action that is likely to adversely affect the confidence of the public in the integrity of the Board or of ­WMATA.”

Dorsey said he realized he had neglected to disclose the union contribution to Metro after Audrey Clement, an opponent in his campaign for reelection in Arlington, criticized him for both the $10,000 ATU donation and an equally large one from the International Brotherhood of Electrical Workers. She said the money should disqualify him from discussions or votes involving labor negotiations.

“It had been brought up on the campaign, that unions make up a large portion of my campaign donations,” Dorsey said. “In reflecting on that, I wanted to make sure I had done everything properly. I realized I hadn’t done my WMATA disclosure.”

In a Washington Post article published Oct. 31, a day after he submitted the revised disclosure to Metro, Dorsey said he had publicly disclosed the donations and abided by all ethics requirements of Metro and the county.

“I’ve long been a friend of labor,” Dorsey said then. “It seems entirely consistent that I’d get support from them. If and when there is a time when I need to recuse myself [from votes or discussions] at Metro, I will.”