Donald Trump’s pick for national intelligence director, John Ratcliffe, withdrew from consideration Friday after just five days as he faced growing questions about his experience and qualifications.

The move underscored the uncertainty over his confirmation prospects. Democrats openly dismissed the Republican congressman from Texas as an unqualified partisan, and Republicans offered only lukewarm and tentative expressions of support.

The announcement leaves the intelligence community without a permanent, Senate-confirmed leader at a time when the US government is grappling with North Korea’s nuclear ambitions, the prospect of war with Iran, and the anticipated efforts of Russia or other foreign governments to interfere in the American political system.

Ratcliffe is a frequent Trump defender who fiercely questioned the former special counsel Robert Mueller during his testimony before the House Judiciary Committee hearing last week.

Even as Mueller laid bare concerns that Russia was working to interfere with US elections again, Ratcliffe remained focused on the possibility that US intelligence agencies had overly relied on unverified opposition research in investigating the Trump campaign’s ties to Russia.

His performance clearly made a splash with Donald Trump, who subsequently nominated him to become the next director of national intelligence, replacing Dan Coats, who repeatedly clashed with Trump and revealed last weekend that he was leaving the post.

At the time, former intelligence officials warned the nomination was an attempt to to “neutralise” US spy agencies as an independent and objective voice on global affairs.

“I fear that there is a slow takeover of the norms and procedures of governance by this president, amassing unprecedented executive power,” Rolf Mowatt-Larssen, a former CIA intelligence officer, told the Guardian on Monday. “To do that, he needs to neutralise, or at least silence, the intelligence community. He has been doing that for three years, but this takes it to the new level.”

Republicans had their doubts, and made noises behind the scenes that he would need to show he can move beyond the die-hard conservative persona that has made him a star in the House and on Fox News, but less well known among the senators who would decide whether to confirm him, the New York Times wrote.

In his own statement, Ratcliffe said he remained convinced that he could have done the job “with the objectivity, fairness and integrity that our intelligence agencies need and deserve”.

“However,” he added, “I do not wish for a national security and intelligence debate surrounding my confirmation, however untrue, to become a purely political and partisan issue.”

Democrats strongly criticized Ratcliffe’s partisanship, noting he was a vocal skeptic of former special counsel Mueller’s investigation. They said he wasn’t suited for a position that is designed to objectively oversee the nation’s intelligence agencies.

The White House, in recent days, fielded a number of calls from Republicans also wary of Ratlciffe’s confirmation chances and uncomfortable with his qualifications, according to two administration officials who spoke to the Associated Press.

Taking their cue from the president’s instinct to push back against the media and fight for problematic nominees, White House officials initially planned to rally around the choice. But Ratcliffe himself expressed concern to the West Wing about the scrutiny, the administration officials said.

They said that while the president has long admired Ratcliffe’s interviews in which he defended the White House, as well as his performance in the Mueller hearings, Trump grew convinced that the nomination battle would become a distraction – and was quick, as he often is, to blame the media for treating his administration unfairly.

In a tweet Friday, Trump said Ratcliffe had decided to stay in Congress so as to avoid “months of slander and libel”.

The scuttled nomination deepened questions about the White House’s seemingly haphazard vetting process.

Senator Richard Burr, the chairman of the Senate intelligence committee, said in a statement that he respects Ratcliffe’s decision and he is committed to moving the official nomination through committee. “There is no substitute for having a Senate-confirmed director in place to lead our intelligence community,” Burr said.

Until then, lawmakers have urged Trump to put Sue Gordon, Coats’ No 2, in charge once Coats steps down. But it’s unclear whether he will. Trump told reporters Friday that “certainly she will be considered” for the acting director position.

For Coats’ permanent replacement, Trump told reporters that he has a list of three people he’s working on over the weekend, and “probably Monday I’ll give you an answer”.