The director of the Office of Government Ethics is resigning.

Walter M. Shaub Jr., the government’s top ethics watchdog who has repeatedly gone head-to-head with the Trump administration over conflicts of interest, said on Thursday that he was calling it quits.

Mr. Shaub’s five-year term as the director of the Office of Government Ethics is not set to expire until January, but with little chance of renewal and an appealing offer in hand from a nonpartisan advocacy group, he said the time was right to leave.

“There isn’t much more I could accomplish at the Office of Government Ethics, given the current situation,” Mr. Shaub said in an interview on Thursday. “O.G.E.’s recent experiences have made it clear that the ethics program needs to be strengthened.”

But of course now that Trump will be appointing a new director, it won’t be.

In a short letter informing President Trump of his decision, Mr. Shaub did not offer a specific reason for his departure but extolled “the principle that public service is a public trust, requiring employees to place loyalty to the Constitution, the laws and ethical principles above private gain.” He had not been pressured to resign, he said.

A rather pointed observation, but it won’t make a dent in Trump, because nothing does. Narcissists are like that.

The intensity of feeling over what is usually an obscure job speaks to the central role ethics have come to play in Mr. Trump’s Washington, where the vast holdings of the president and his cabinet, as well as an influx of advisers from businesses and lobbying firms, have raised a rash of accusations of conflicts of interest.

A rash of accusations that reflect a rash of realities.

Mr. Shaub, 46, has faced an uncertain future at the agency since Mr. Trump took office in January. In the weeks between the president’s unexpected election victory and his inauguration, Mr. Shaub had taken an extraordinary gamble: He advocated very publicly on Twitter, and in a rare public speech, that Mr. Trump liquidate his vast business and personal holdings. The arrangement, Mr. Shaub argued, was the only truly ethical option.

Mr. Trump did not heed his advice, and by the middle of January, Mr. Shaub thought he might be fired. To minimize his attachment to the position, he packed up the personal possessions that filled his office.

But he was not fired, even as he continued to spar with Mr. Trump’s aides over a range of ethical concerns, including the ethics office’s authority to exercise oversight of the White House.

In February, he recommended that the White House disciplineKellyanne Conway, a top adviser to the president, after she made an on-air endorsement of the clothing line of Ivanka Trump, the president’s daughter. The White House Counsel’s Office disagreed and took no disciplinary action.

More recently, Mr. Shaub and the administration fought over a routine request by the ethics office for copies of waivers issued to White House appointees to work in the Trump administration. The Office of Management and Budget initially balked at the request, challenging Mr. Shaub’s legal authority even to ask for the information and asking him to withdraw it. After Mr. Shaub fired back with a stern 10-page letter shooting down the argument, the White House backed down.

The White House eventually released the waivers, showing it had granted at least a dozen exemptions for aides to work on policy matters they had handled as lobbyists or to engage with former colleagues in private-sector jobs. Mr. Shaub objected to the fact that many of the waivers were undated and unsigned, and that some gave approvals for acts retroactively.

In short, Trump presides over an ethical sewer.