WASHINGTON • The legal and political threats hanging over the Trump presidency have hampered efforts by the White House to fill the top ranks of government.

President Donald Trump's firing of Federal Bureau of Investigation (FBI) director James Comey last month and the widening probe into Russian interference during the presidential election have made hiring even harder, say former federal officials, party activists, lobbyists and candidates whom Trump officials have tried to recruit.

Republicans say they are turning down job offers to work for a chief executive whose volatile temperament makes them nervous.

They are asking headhunters if their reputations could suffer permanent damage, according to 27 people interviewed by The Washington Post to assess what is becoming a debilitating factor in recruiting political appointees.

The hiring challenge complicates the already slow pace at which Mr Trump is filling senior leadership jobs across government.

The White House disputed the notion that the administration has a hiring problem, and noted that its candidates must be vetted by the FBI and the Office of Government Ethics before being announced publicly, which might contribute to the perception that there is a delay in filling key posts.

"I have people knocking down my door to talk to the presidential personnel office," said White House press secretary Sean Spicer. "There is a huge demand to join this administration."

The Senate has 25 working days until it breaks for the August recess.

At this point, Mr Trump has 43 confirmed appointees for senior posts, compared with the 151 top political appointees confirmed by mid-June in President Barack Obama's first term and the 130 under President George Bush, based on data tracked by The Post and the Centre for Presidential Transition, which is run by the non-partisan Partnership for Public Service.

For Cabinet posts, the median wait between nomination and Senate vote for Mr Trump was 25 days, according to data collected by The Post. In contrast, Mr Obama's nominees faced a median wait of two days, while Mr Bush had a median wait of zero days.

A White House official said about 200 people are being vetted for senior-level posts. Potential candidates are watching Mr Trump's behaviour and monitoring his treatment of senior officials.

"Trump is becoming radioactive, and it's accelerating," said Mr Bill Valdez, a former senior official with the Department of Energy who is now president of the Senior Executives Association, which represents 6,000 top federal leaders.

"He just threw Jeff Sessions under the bus," said Mr Valdez, referring to recent reports that the President is furious at the Attorney-General for recusing himself from the Russia investigation.

Yesterday, a member of Mr Trump's legal team said the President is not under investigation by the probe's special counsel - an assessment at odds with a Washington Post report last week and seemingly with a tweet by Mr Trump himself last Friday.

"Let me be very clear here, as it has been since the beginning, the President is not and has not been under investigation for obstruction," said lawyer Jay Sekulow on an NBC programme.

The Post reported last week that special counsel Robert Mueller III, who was appointed to oversee the investigation into Russia's role in the election last year, is interviewing senior intelligence officials as part of a widening probe that now includes an examination of whether Mr Trump attempted to obstruct justice.

WASHINGTON POST