Donald Trump has urged a controversial loyalist he installed as the country’s top intelligence official to fire “a lot of people” overseeing intelligence for the US federal government.

The US president said Bill Pulte, who has no previous experience in the intelligence sphere, is “less shackled” because he has only been appointed director of national intelligence temporarily.

Amid bipartisan concern over his appointment, Trump has told Pulte that he believes the office of the director of national intelligence – which oversees more than a dozen intelligence agencies and departments – is “unnecessary and/or too big”, the president told the Wall Street Journal.

“I’d like to see it smaller,” Trump told the Journal. “I think there are a lot of people in there that shouldn’t be there.”

Asked whether he was calling on Pulte to fire people, Trump replied that he wants his ally to “start the process”, adding that whoever he nominates to take the job permanently can continue it.

While Trump has tried in recent days to quell unease over Pulte’s appointment, insisting he was not going to be permanently in the job, the president suggested on Friday that this could help Pulte to take more drastic action. “You’re less shackled,” Trump told the Journal. “It sort of gives you more power, you know, for a somewhat limited period of time.”

His remarks were published hours after a closely watched vote in the US Senate underlined the scale of concern over Pulte’s new position – even within the president’s own party.

Seven Republican senators joined Democrats early on Friday morning to block the extension of a powerful government surveillance program.

The renewal had been in question amid bipartisan concern over the US president’s appointment of Bill Pulte, a major Republican donor and heir to a home construction fortune, to serve as acting director of national intelligence.

The Senate majority leader, John Thune, a South Dakota Republican, said following the 47-52 vote that the chamber “will take another run at it” next week, but expressed little confidence the measure would pass.

Democrats, he said, had taken a “terribly irresponsible position” by opposing the extension to section 702 of the Foreign Intelligence Surveillance Act (Fisa). The program permits US intelligence agencies to collect communications of foreign targets operating outside the country without a warrant.

Critics say that a wide array of domestic communications can be also be swept up without a warrant ever being sought because they may pass through US servers or involve US contacts.

The program is set to expire next week, and Friday morning’s procedural measure, if it had passed, would have set up a final Senate vote on the extension before a 12 June congressional deadline.

“The naming of Pulte to that position, although the timing arguably wasn’t the best, I still don’t think it ought to derail something that’s this important,” Thune said.

He did not mention the Republican senators who crossed the aisle to join Democrats to vote against the Fisa extension pathway.

It mirrored bitter infighting in Republican ranks in the House of Representatives last month, before Pulte’s appointment, over the warrantless spying program. An 18-month extension to section 702 was defeated 197-228 after 20 Republican representatives rebelled, and the chamber eventually settled on a 45-day “negotiation” period.

Republican discontent in the Senate, meanwhile, centered on Trump’s advancement of Pulte, who leads the Federal Housing Finance Agency (FHFA), and has used his oversight role of the housing lenders Fannie Mae and Freddie Mac to publicly level a string of extraordinary allegations at Trump’s political opponents and enemies.

“We don’t need a weaponized” national intelligence director, Thune told reporters on Tuesday, warning that Pulte would face “a lengthy road ahead of him” if nominated permanently.

One day later, the Virginia Democrat Mark Warner, vice-chair of the Senate intelligence committee, told NPR that Pulte was only selected because he was “100% loyal to doing anything and everything President Trump demands”.

Warner said appointing a person with no intelligence, law enforcement or congressional experience would amount to “almost unilaterally disarming” against US adversaries including Russia, China and Iran. “We have no idea whether the individual even has a security clearance,” he said.

One Democrat, John Fetterman of Pennsylvania, joined 46 Republican senators on the losing side of Friday’s vote.

Punchbowl News reported that Warner personally asked Thune to use his influence with the White House to reverse Pulte’s appointment, with Democratic sources making clear a bipartisan deal on section 702 could collapse if Trump refused.

On Thursday, Trump escalated concerns over what Pulte will do as acting intelligence director by suggesting he would investigate unfounded allegation of election cheating. “He’s a very smart guy,” Trump said, “and you may find out some things about the rigged elections, etc, etc.”

Trump alleged this week without evidence that Democrats were cheating in California’s primaries. He also claimed the US attorney’s office in Los Angeles was investigating. The US attorney’s office said it had no comment.

The Associated Press contributed reporting