In his tenure as the District’s longest-serving council member, a reign now in its third decade, Jack Evans has been subject to periodic questions about his ethical conduct, none of which have prevented him from winning reelection seven times.

His cakewalk may be over.

For the first time, a federal grand jury issued a subpoena in September for Evans’s records to determine whether he used his public office to help a private company. And Tuesday, in a sign of an expanding probe, prosecutors also subpoenaed records pertaining to Evans from the office of Mayor Muriel E Bowser (D) and the 13-member D.C. Council.

In addition, emails obtained by The Washington Post show that Evans, in his own words, repeatedly offered to use on behalf of prospective clients the network of political connections and the influence he built as a lawmaker and as chairman of the Washington Metropolitan Area Transit Authority.

A close ally of Bowser’s, Evans (D-Ward 2) is facing an impending council reprimand, a WMATA ethics investigation and demands from more than two dozen neighborhood leaders that he be stripped of his chairmanship of the council’s finance and revenue committee.

By last Wednesday, Democratic operatives were openly questioning whether Evans — until now a sure bet in a ward that includes Georgetown, Dupont Circle and downtown — can win reelection next year.

At the moment, Evans’s greatest vulnerability is the grand jury investigation, which appears to have begun with questions about his relationship with a digital-sign company, Digi Outdoor Media, and legislation he drafted in 2016 that would have benefited the company. That probe appears to have widened; the subpoenas issued to the Bowser administration and the D.C. Council in the past week suggest that investigators are also looking into relationships between Evans and a number of real estate developers, law firms and lobbyists.

“There’s a Teflon aspect to Jack. He knows everyone, he’s probably done something for a lot of them, and he’s an affable guy,” said Chuck Thies, a political consultant who has worked for Evans. “The difference now is when people hear ‘grand jury,’ ‘subpoena’ and ‘U.S. attorney,’ they think criminal behavior. The fundraising can dry up.”

The latest missteps by Evans, a survivor of more than a few unflattering episodes in his career, are a stunning turn for a business-friendly politician who has been pivotal to the kinds of projects that have defined the District’s economic renaissance: Nationals Park, the Walter E. Washington Convention Center, and what is now known as the Capital One Arena.

A bon vivant who twice lost races for mayor, he is a regular on the black-tie circuit and crowds his office walls with grip-and-grin photos of himself with celebrities, politicians, developers and lobbyists, sometimes rearranging the display to more prominently feature whoever is meeting with him on a particular day.

Tom Lindenfeld, a political consultant whose clients have included Bowser and former mayor Adrian M. Fenty (D), said Evans is damaged politically — perhaps fatally — no matter how prosecutors proceed, because of the “specter of unethical or even corrupt behavior.”

“You only score on offense, and right now Jack is entirely on defense,” Lindenfeld said. “Anytime you’re explaining, you’re losing.”

Evans, in a statement to reporters last week that he delivered without taking questions, apologized for his conduct, though he did not explain what he had done wrong.

As he left a civic association meeting Thursday, Evans, in a brief interview, suggested that his mistake was using his council email to send business proposals to several prospective employers. The Post obtained copies of emails through a Freedom of Information Act request.

The records show that Evans sent the proposals in 2015 and 2018. In one email, sent to Nelson Mullins, a law firm that had lobbied his council office, Evans offered his political connections and influence to help the firm’s clients.

“It was just a mistake, to be honest with you,” Evans said. “And that’s it. In a hurry. Not thinking. You know? And it just happened by mistake.”

But Evans said his conduct was not illegal or unethical, and he brushed aside questions about whether it was improper to sell his political influence while serving as a public official.

“It was a mistake,” he said. “I believe I’ve done nothing wrong. And other than what I just said — making mistakes — I hope my constituents will continue to support me.”

Less than 12 hours after issuing his apology at city hall, Evans stood before the Sheridan-Kalorama Neighborhood Council, offering a breezy assessment of the District’s economy and public schools before volunteering to answer questions.

Potholes, road repairs and trash pickup were the hot topics, along with the dearth of weekend Metro service.

No one mentioned the grand jury investigating Evans or the council’s impending reprimand.

“Jack does a great job. You look out for us, and we appreciate that,” Chris Chapin, the group’s outgoing president, said as Evans headed for the exit.

For years, Evans has been a reliable presence at civic meetings across his ward, which includes K Street NW, Foggy Bottom and portions of the Seventh and 14th street corridors. By all accounts, he is responsive to his constituents, a mix of affluent homeowners on the West End, the gay community that’s centered around Dupont and Logan circles, African Americans around Mount Vernon Square, and downtown law firms and corporations.

A career tactician, he aligns himself with whoever is mayor, even if he ran against the person, as was the case with Bowser, whom he derided as a lightweight during the 2014 Democratic primary. At one point, he sent out a mass mailing of a blank white page to lampoon her achievements as a council member.

After Bowser won the election, few Democrats were more enthusiastic about her mayoralty than Evans.

Elected to the council in 1990 as an opponent of unrestrained development, Evans soon became a champion of projects that redefined Washington, and he cultivated relationships with developers, lawyers and corporate executives who poured money into his campaigns and made him virtually impossible to defeat.

Barbara Lang, a former head of the D.C. Chamber of Commerce, said the business community relies on Evans to oppose legislation “that would be a defeat for the business community, large and small. You could count on him to manage the finances in a way that the business community supports.”

The prospect of his political demise, Lang said, is a source of “some anxiety” among business owners, who she said are adopting “a wait-and-see attitude.”

“You won’t see anybody coming out and beating up Jack just yet,” she said. “They are disappointed — how do you get into this kind of thing? — but people will talk privately. We’ll see how it moves forward.”

In 2008, as he sought reelection, Evans faced challenger Cary Silverman, a lawyer, who hammered the incumbent for the lucrative salary he was drawing from Patton Boggs, a powerful lobbying firm, while serving on the council.

District law allows city council members to hold jobs outside their full-time government work. Despite this, just two of the 13 council members reported any significant outside income in recent required disclosures. One was Mary M. Cheh (D-Ward 3), who teaches constitutional law at George Washington University. The other was Evans.

In the 2008 race, Silverman wondered whether Evans’s mission for Patton Boggs was to influence his council colleagues on legislation that was important to the firm’s clients.

“These questions have always been there with Jack,” Silverman said in an interview. He lost the Democratic primary to Evans by nearly 30 percentage points, outraised by 10 to 1 and unable to arouse voter anger about Evans’s employment.

“People are concerned with the day-to-day and whether their neighborhood is safe and less about their council member making money on the side,” Silverman said.

By 2008, Evans had faced scrutiny over his use of his political action committee — “Jack PAC” — from which he drew thousands of dollars to reimburse himself for travel and entertainment expenses. The expenses included $6,772 he spent for a friend to accompany him on an official trip to China. The Office of Campaign Finance ruled that Evans had not violated the law but recommended that he reimburse the PAC.

Evans also faced criticism in 2011 for using his constituent services fund — money that council members raise and most use to help residents with emergencies such as missed rent payments or overdue electricity bills. Over the preceding decade, Evans had used his fund to buy $135,000 worth of tickets to events including Washington Nationals, Wizards and Capitals games.

While Evans at the time deemed the practice “perfectly legal,” saying his constituents received some of the tickets, his colleagues and community leaders questioned the propriety of the spending.

The criticism did not stop him. Since then, Evans has used his constituent services fund to purchase $207,000 in tickets to Nationals, Wizards and Capitals games, records show. Compared with his colleagues, Evans maintains by far the fattest constituent services fund.

“He seems to be oblivious to the kinds of trouble he gets himself into,” said Craig Holman, government affairs lobbyist for Public Citizen, the nonprofit public advocacy organization. “He either doesn’t care or he’s unaware of the seriousness of these transgressions.”

That Evans has survived politically reflects that the D.C. government has not “taken ethics seriously,” Holman said. “It suggests that the D.C. government was fairly comfortable with a low standard of ethics.”

At the same time, Evans has always recovered his footing.

“Over time, he has learned that all he had to do was hold tight and the next thing would come along, involving someone else, and that would become the story of the day and it would all go away,” said a longtime associate, speaking on the condition of anonymity to be candid. “In the meantime, you tout your relationship with the mayor, you talk about the city’s triple bond rating and you have staff to deal with little things.”

“He has this uncanny ability to walk up to the line and never cross it,” the associate said, adding that Evans’s current troubles “are different.”

“There has never been a grand jury investigation subpoena before,” he said.

“He has a strong base of support,” the associate said. “The question is, ‘Who’s paying attention?’ ”

In his ward, community leaders and supporters have largely refrained from criticizing Evans.

Barbara Kahlow, an officer of the West End Citizens Association, described Evans’s use of council email to solicit business as a show of “sloppiness and a lapse in judgment.” But she said she would support him for reelection because “he has helped our community in major ways.”

Leroy Thorpe, of the Shaw Community East Central Civic Association, said that Evans should be able to endure because he has apologized. A council reprimand would be ample punishment, he said. “We love Jack,” Thorpe said, recalling that Evans helped Shaw leaders combat crime during the 1980s. “He’s a human being. He makes errors. But he’s a good man.”

John Fanning, an advisory neighborhood commissioner in Logan Circle, said ward leaders are afraid to criticize Evans.

“If for some reason he loses his influence, people lose access to opportunity,” Fanning said. “We don’t know where this whole investigation is going to lead, and individuals fear that he could cut them off if they speak out.”

As he left the civic association meeting Thursday night, Evans appeared drawn and chastened, a shadow of the man who once inspired the Washington City Paper headline, “Swagger Jack.”

Asked whether he would survive, Evans said, “I think so. I hope so.”

“Treat me nicely, will you?” he said, before getting in his car and driving away.

Steve Thompson and Fenit Nirrapil contributed to this report.