WASHINGTON — Temporary status is a seemingly permanent condition of the Trump administration.

The resignation of Kirstjen Nielsen as Homeland Security secretary Sunday means that another Cabinet officer who reports directly to President Trump will have the word “acting’’ next to the official title at a major department of government.

Interim secretaries are also in place at the Departments of Defense and of the Interior, and at the Office of Management and Budget, the Small Business Administration, and ambassador’s office at the United Nations. Mick Mulvaney, Trump’s chief of staff, is also serving in an acting capacity.

“I like acting. It gives me more flexibility. Do you understand that?’’ Trump told reporters in January before departing to Camp David. “I like acting. So we have a few that are acting. We have a great, great Cabinet.’’

But there are concerns about having men and women in such high-level jobs without having been subjected to Senate confirmation for those posts. Leaving Cabinet secretaries unconfirmed in their roles could give the president even more leverage over them, or could leave them without full authority in the job.

“The Senate grappled with this question in the very first Congress when it ordered George Washington to send nominations to the Hill at a reasonable pace,’’ said Paul Light, a professor of public service at New York University who has written extensively on the appointment process. “Senators rightly worried that presidents might use acting appointees to evade oversight and institutional prerogatives. Yet, we haven’t heard a word from the Senate on the Trump administration’s abuse of its acting authority.’’

Justice Clarence Thomas argued in a concurring opinion in a 2017 case that there was seemingly no constitutional basis for having “acting’’ Cabinet members and that there needed to be limits on a president’s power to fill the highest positions without Senate confirmation.

The Constitution requires that the president obtain “the Advice and Consent of the Senate’’ before appointing Cabinet officials. Legal scholars also questioned the president’s power to use the “acting’’ authority in replacing Nielsen.

“To me, the real difference is avoiding Senate confirmation — either because the individuals he wants running these agencies can’t be confirmed even by a Republican-controlled Senate, or because he’s worried about the kinds of questions they’d have to answer and or concessions they’d have to make in order to be confirmed,’’ said Stephen Vladeck, a law professor at the University of Texas. “Either way, that’s an alarming argument for bypassing a Senate controlled by his own party.’’

Trump announced in a tweet Sunday that Kevin McAleenan, 47, commissioner of US Customs and Border Protection, will be Nielsen’s replacement, as “acting’’ Homeland Security secretary at a time when the president has said that there is a security crisis at the border with Mexico because of a flood of migrants trying to gain entry into the United States.

Some acting officials like Patrick M. Shanahan, the acting defense secretary who had been deputy defense secretary, have been confirmed by the Senate but not in the post in which they currently serve. David Bernhardt, the acting Interior secretary, had already been confirmed as the department’s deputy and is undergoing confirmation by the Senate for the top job.

Trump had long said he was satisfied with the performance of Nielsen. He expressed similar optimism for her acting successor.

“I have confidence that Kevin will do a great job!’’ Trump said in his tweet.

No matter who Trump would have selected, it will take time to get fully operational. Government agencies, Light noted, must “wade through piles of internal paperwork assigning responsibilities and signature authorities to one acting after another.’’

Career government officials “wonder when vacancies will be filled, how long the actings will stay, and whether they’ve got the right name on the organization chart to move forward on major issues such as the Max 8 groundings,’’ he said, referring to the airliner involved in two fatal crashes.

Oversight by ethics and accountability agencies within the government is also constrained. “The result is a fundamental collapse in ordinary accountability,’’ Light said.

In her resignation letter, Nielsen said she hoped the incoming secretary would “have the support of Congress and the courts in fixing the laws which have impeded our ability to fully secure America’s borders and which have contributed to discord in our nation’s discourse.’’

But the support of Congress may be difficult to obtain, notably among Democrats who have said Trump is usurping the role of a coequal branch of government.

“Without confirmation hearings, there’s less of a chance for the Senate to meaningfully play a role in identifying who will be in charge of these critical government functions, and thus less accountability for episodes like Acting Secretary Shanahan’s ties to Boeing,’’ Vladeck said. “Second, an acting secretary may have the same control over his or her own agency as someone who is Senate confirmed, but traditionally, Senate-confirmed officers have more pull in any interagency conflict, and so it has the effect of skewing the authority of different agencies toward those with permanent heads.’’