The new acting director of national intelligence has begun cutting staff days into his new role, but the initial round will be smaller than some officials and members of Congress expected, former officials said.

Bill Pulte, who was installed in the position on Friday, has fired six intelligence officials, including career officers and political appointees. Another 45 officers from other spy agencies who had been lent to the office were sent back to their home agencies, the former officials said.

Current and former officials said Mr. Pulte considered much deeper cuts and bigger structural changes, like transferring the office’s counterterrorism and counterintelligence centers to other departments or agencies, but had decided to hold off.

It was not clear whether Mr. Pulte would try to push out more officials.

Some members of Congress from both parties have said that a smaller Office of the Director of National Intelligence could be reasonable, as long as it has enough people to provide oversight and coordination of the other 18 spy agencies. But lawmakers have expressed concern about President Trump’s decision to appoint Mr. Pulte, a political loyalist with no relevant experience.

Democratic members of Congress have warned against deep cuts, saying such reductions in force or restructuring of the office would be better left for a Senate-confirmed director. They likened Mr. Pulte to a hatchet man sent by Mr. Trump to fire veteran national security officials while seeking retribution against the president’s enemies.

It is unlikely that the congressional warning carried much weight with Mr. Pulte, but U.S. officials said some White House officials also urged caution. The easiest cuts to make at the office would be to the counterterrorism center, some former officials said, because it is so large. But some senior officials warned that cutting terrorism experts creates political risk, according to current and former officials.

About 400 intelligence officers work in the counterterrorism center, the largest concentration of employees inside the office. The center has been monitoring threats against the World Cup, as well as from cartels, a major priority for the Trump administration.

“Today, I spent time with the National Counterterrorism Center team, who is doing an incredible job protecting our Country under President Trump’s leadership,” Mr. Pulte said Tuesday evening on social media. “The room was filled with true professionals and American patriots. It is a privilege to work beside them.”

Despite those comments, a former official at the center said that “nobody feels safe.”

Before Mr. Pulte’s arrival, there were about 1,300 full-time employees at the office of national intelligence and 300 to 400 contractors, according to U.S. officials.

His predecessor, Tulsi Gabbard, who stepped down on Friday, oversaw a large downsizing and reorganization of the spy agency as well, cutting about 40 percent of the staff.

Mr. Pulte’s cuts were reported earlier by CBS News.

Asked for comment, a White House official referred to a June 10 social media post in which Mr. Trump said he had asked Mr. Pulte “to execute the immediate and needed downsizing of the office, reverting staff to their home agencies.”

A request for comment from the Office of the Director of National Intelligence was not returned. Ms. Gabbard’s representatives have left the office, and it is not clear who Mr. Pulte has appointed to replace them.

Mr. Pulte was installed as the acting director of national intelligence last week after Mr. Trump pulled back his choice for a permanent replacement, Jay Clayton. The Senate was poised to quickly install Mr. Clayton to the office, but Mr. Trump appears to have wanted to give Mr. Pulte some time to serve as the acting director.

Mr. Pulte’s agenda is not clear. So far, he has purged some of Ms. Gabbard’s top aides and had heroic images of Mr. Trump posted on the office’s social media feed.

Mr. Trump has suggested that Mr. Pulte could be “very effective” in a short amount of time and would share information with the public about “rigged elections.”

Ms. Gabbard had begun some investigations of voting machines, though she had not published her report before she left. Mr. Trump has praised her for supervising an F.B.I. raid in Fulton County, Ga., where the bureau seized ballots from the 2020 election.

Mr. Pulte could build on Ms. Gabbard’s efforts, or take other steps to investigate Mr. Trump’s false claims of voter fraud in the 2020 election or raise concerns about the midterm elections.

He could also release other information, potentially about Russian meddling in the 2016 election. Mr. Trump has long been obsessed with the F.B.I.’s investigation of his campaign and the intelligence community’s assessments of Russian interference on his behalf.