HARDLY ANY time passed between President-elect Donald Trump’s announcement last Wednesday of his plan to separate himself from his sprawling business empire and ethic watchdogs’ condemnation of the plan as deficient. Chief among the detractors was Walter M. Shaub Jr., director of the Office of Government Ethics (OGE), an independent agency charged with overseeing conflict-of-interest and other rules in the executive branch. Mr. Shaub has emerged as one of Mr. Trump’s chief critics — and, unfortunately, as a center of attention.

The law gives Mr. Shaub wide authority to help police executive branch “employees” and “officers.” But it exempts the president and vice president from key conflict-of-interest requirements. In a speech at the Brookings Institution last Wednesday, Mr. Shaub acknowledged this exemption. He nevertheless noted that the modern expectation is that “the president should act as though the financial conflict-of-interest law applied,” noting that “the signals a president sends set the tone for ethics across the executive branch.”

Mr. Shaub made some good points, but it’s not clear it was wise for him to do so. He is not the director of a nonprofit government watchdog; he is a federal officer operating under the color of law, empowered to help enforce specific statutes. In his comments he was operating outside his lane.

If Mr. Shaub’s freelancing was unsettling, however, the GOP’s overreaction was downright chilling. Incoming White House chief of staff Reince Priebus warned Mr. Shaub “to be careful.” House Oversight and Government Reform Committee Chairman Jason Chaffetz (R-Utah) sent a letter to Mr. Shaub summoning him to a deposition-style grilling, noting that the oversight committee is responsible for authorizing the OGE in law.

As Congress’s chief watchdog, with an open-ended charge to review all sorts of executive branch activity, Mr. Chaffetz should be raising questions about Mr. Trump’s ethics plan. Before November’s election, he promised “years” of investigations of Hillary Clinton, if she won. His tune changed after Mr. Trump’s victory; he said Sunday he has no interest in a “fishing expedition” to assess Mr. Trump’s business entanglements. Yet he will use valuable committee resources assailing a federal ethics officer for what amounts to modestly concerning behavior.

(Jenny Starrs/The Washington Post)

Some observers worry that Mr. Chaffetz might even defund or otherwise curb the OGE, which, whatever the merits of Mr. Shaub’s comments, performs valuable work. Just as it has for every other recent presidential administration, the office has helped a variety of Trump nominees unwind their financial conflicts, aiding them so they can be confident they will not enter office under an ethical cloud. Mr. Chaffetz is already prioritizing partisanship over responsibility. Undercutting the executive branch’s ethics office would represent a larger failing.

Mr. Shaub should stop picking fights with the president-elect, unless and until Congress gives him the clear responsibility to do so. Mr. Chaffetz should spend his time on more consequential issues.