U.S. President Donald Trump's pick for national intelligence director, Texas Rep. John Ratcliffe, withdrew from consideration Friday amid concerns in Congress about his experience and qualifications.

The move, coming just five days after Trump announced plans to nominate Ratcliffe, underscored the uncertainty over his confirmation prospects. Democrats openly dismissed the Republican congressman 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 U.S. government is grappling with North Korea's nuclear capabilities, the prospect of war with Iran and the anticipated efforts of Russia or other foreign governments to interference in the American political system.

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

Trump didn't cite specific media reports, though multiple stories in the last week have questioned Ratcliffe's qualifications and suggested that he had misrepresented his experience as a federal prosecutor in Texas.

Is he qualified for that job? — Sen. James Lankford

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

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

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."

Our great Republican Congressman John Ratcliffe is being treated very unfairly by the LameStream Media. Rather than going through months of slander and libel, I explained to John how miserable it would be for him and his family to deal with these people.... —@realDonaldTrump

"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."

Ratcliffe would have replaced former intelligence director Dan Coats, who repeatedly clashed with Trump and announced his resignation on Sunday.

Small-town mayor

North Carolina Sen. 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.

Senate Republicans were publicly lukewarm on Ratcliffe's nomination. Some expressed concerns that the House lawmaker, who was viewed as a partisan, did not come with the gravitas of Coats, who had longtime relations as a former senator. Some senators said they had never even heard of him before his questioning of Mueller.

Senate Majority Leader Mitch McConnell signalled a wait-and-see approach on Tuesday, saying only that he looked forward to meeting with Ratcliffe and discussing his background.

Ratcliffe would have succeeded Daniel Coats, who repeatedly clashed with Trump and announced his resignation on Sunday. (Andrew Harnik/Associated Press)

McConnell, the top Republican in the Senate, said that "generally speaking, I'd lean toward the president's nominees." But he declined to fully endorse Ratcliffe, who served as a mayor of a small Texas town and a U.S. attorney before being elected to Congress in 2014.

Oklahoma Sen. James Lankford, a Republican who is a former member of the committee, appeared more concerned, saying that Ratcliffe will have "some catching up to do" in the role. He said Coats, who had spent decades in Washington, clearly had more experience.

"Is he qualified for that job?" Lankford asked, referring to Ratcliffe. "He's a qualified, gifted individual, but I think it will take some time for him to do some on the job training to be able to get into it."

The director of national intelligence oversees the various U.S. spy agencies, including the CIA. (Larry Downing/Reuters)

Maine Sen. Susan Collins, a critical swing vote for the Republicans, who sits on the intelligence panel, praised Coats and said the intelligence position is very important to her because she co-wrote the legislation that created it 15 years ago. She said she had never heard of Ratcliffe before last week, so she couldn't comment on his qualifications, but added that she wants "an independent, well-qualified individual in that post."

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

Trump did little to assuage those concerns, saying of Ratcliffe on Tuesday: "I think we need somebody like that there. We need somebody strong that can really rein it in. Because, as I think you've all learned, the intelligence agencies have run amok. They've run amok."

Sen. Mark Warner, the top Democrat on the intelligence committee, said he wanted a nominee like Coats: "someone with a deep knowledge of the intelligence community, respect for the hard work intelligence professionals do to keep us safe, and the independence and integrity to speak truth to power when necessary."