D.C. Council Member Jack Evans said Tuesday that he will not testify under oath in response to an investigation that found he repeatedly violated ethics rules in his private business dealings with companies that had interests before city government.

The longest-serving local lawmaker is fighting for his political career in the aftermath of multiple investigations and an ongoing federal probe into the overlap between his public service and private employment.

The rest of the 13-member council is weighing what disciplinary action, if any, to take against Evans (D-Ward 2) and invited him to address them and answer questions at a public meeting next week.

But in a letter Tuesday, Evans said he answered enough questions in 15 hours of interviews with lawyers hired by the council. During those sessions with lawyers from O’Melveny & Myers, Evans was not under oath.

“I have decided there really should be no reason to duplicate these questions and answers and appear before the Committee,” Evans wrote.

Lawyers from O’Melveny & Myers found that Evans repeatedly used his office to assist companies that paid him hundreds of thousands of dollars for consulting services that he could not fully explain. The investigators also said Evans failed to disclose those clients and to recognize conflicts of interest.

In his letter, Evans acknowledged mistakes when he ­transitioned in 2016 from working at law firms to running his own consulting business.

“In retrospect, it was not a good idea to set up my own business,” Evans wrote. “As such, I have closed the business and do not intend to have any outside employment as long as I am a member of the Council.”

Investigators from O’Melveny & Myers examined Evans’s private employment dating to 2014, before he began his private consulting work, and raised questions about his work at law firms that represented entities with business before the council.

Nine lawmakers have urged Evans to resign, and three have said they would vote to expel him if he did not. A majority of D.C. residents also want Evans to step down, according to a recent poll by The Washington Post.

Council member Mary M. Cheh (D-Ward 3), who is leading the internal investigation of Evans, said he has the right to decline to testify.

“If he doesn’t want to appear, I don’t see any point in forcing the issue,” Cheh said. “His letter acknowledges in his own way that he got plenty of due process, plenty of opportunity to be heard and plenty of opportunity to make all sorts of submissions.”

But other lawmakers wanted the opportunity to question Evans.

“We have a whole host of questions around clients and the folks he was doing business with,” said council member Charles Allen (D-Ward 6). “He should come in, and he should be under oath, but it says a lot that he’s not going to do it.”

Mayor Muriel E. Bowser (D) declined to address Evans’s decision.

Cheh said the council will use next Tuesday’s meeting to discuss whether to further investigate Evans and potential disciplinary measures. She said the council could finish its internal probe of Evans before the new year.

Expulsion requires the support of 11 members. Short of expulsion, the council could reprimand Evans, formally censure him or strip him of all committee assignments.

In a letter Tuesday to the D.C. Council, Evans’s legal team said the council should not expel the lawmaker and stressed that voters could decide his fate, if not with a recall then with city elections next year, when his term expires.

“Those processes should determine Mr. Evans’ future,” wrote Abbe Lowell and Mark Tuohey, who are representing Evans. “The Council should not easily or readily disenfranchise the residents of a ward. That would create a precedent that could easily be expanded and misused against anyone who lets that occur.”

Evans, first elected in 1991, has not filed paperwork to run for reelection and faces six challengers in the June Democratic primary if he does.

Evans said in his letter that O’Melveny & Myers concluded he did not knowingly or intentionally break ethics rules.

But those investigators told the council last week that they did not examine whether Evans knew he was breaking ethics rules and considered his state of mind irrelevant.

Evans reiterated Tuesday that he has no intention of stepping down.

“I sincerely regret the difficulties I have put the Members of the Council through during this period and look forward to working with all of you going forward,” Evans wrote. “I intend to focus on representing the residents of Ward 2 on the Council.”