Here's a look at possible Trump picks to replace Comey as FBI director

President Donald Trump's abrupt dismissal of James Comey over alleged mishandling of an investigation into Hillary Clinton's emails has sparked speculation over his likely successor as FBI director.

The White House has said its search will begin immediately, though it did not release a time frame for filling the position.

Deputy Director Andrew McCabe will serve as acting director.

This is just the second time the head of the FBI has been fired. In 1993, FBI deputy director Floyd Clarke filled the position for 44 days after then-President Bill Clinton fired William Sessions in 1993 amid allegations of misuse of government funds.

So who might now be appointed as one of the America's top law enforcers?

McCabe was appointed by Comey in 2016 following the retirement of Mark Giuliano.

He has been with the FB1 for 21 years and has significant experience in counterterrorism and investigations of extremism.

However, McCabe has also come under scrutiny for his investigation into Hillary Clinton's emails.

His impartiality came into question when he failed to recuse himself from the probe even though his wife, Jill, had strong ties with the Democratic Party. She received more than $675,000 in funding when she ran for a Virginia state Senate seat in 2015.

The FBI released a statement at the time saying he "played no role … in fundraising or support of any kind."

However, during campaigning in Florida last year Trump said "the man who was in charge of the investigation of Hillary Clinton accepted essentially from Hillary Clinton $675,000 that went to his wife."

Veteran FBI agent and former Republican House Intelligence Committee Chairman Mike Rogers was previously a frontrunner to lead the FBI before Comey was appointed in 2013.

The Republican served in the Army in the mid to late '80s before joining the FBI's Chicago office as a special agent specialized in organized crime and public corruption.

In 2011, as a member of Congress, Rogers introduced the Cyber Intelligence Sharing and Protection Act (CISPA), allowing government and private companies to share classified cybersecurity knowledge. He said at the time the move would "hopefully keep China (and other countries and hackers) out of American computer networks."

Rogers has also showcased his acumen as a TV personality, having presented a six-part CNN series last year, entitled 'Declassified: Untold Stories of American Spies.'

Fellow ex-FBI man and chief of staff to Comey's predecessor Robert Mueller, Ken Wainstein was also once seen as a top pick for the job.

Previously, he was first assistant attorney general for national security and later homeland security advisor to former President George W. Bush.

Just this week, he advised Director of National Intelligence James Clapper in a Senate subcommittee meeting into Russia's interference in the 2016 election.

Last year, he signed an open letter opposing Trump's presidential nomination.

Another name doing the rounds for the job is Rudy Giuliani, the former New York mayor and federal prosecutor.

Giuliani is an outspoken supporter of Trump.

Though a former Democrat, Giuliani shifted his allegiances to the Republicans in the 1980s and was widely tipped for a position in the new U.S. administration. In January, Trump appointed him as his informal cybersecurity adviser.

Giuliani was spotted outside the Trump Hotel in Washington shortly after Comey's dismissal, and told reporters Trump was "correct to fire Comey," according to Telegraph reports.

He told reporters he was due at the venue for a meeting, although would not specify with whom.

Previous presidents have also turned to former attorneys and judges to fill the top security role.

However, given Trump's track record for filling his new administration with unconventional figures, his recommendation for the leading role could equally be a lesser-known figure or one entirely outside of the law enforcement.

"I would see someone coming from outside of the organization … but to my mind I can't imagine anyone wanting this job," Ron Hosko, Law Enforcement Legal Defense Fund president, told CNBC on Wednesday, likening the job to a burn from a blow torch.

The dismissal of Comey has prompted further calls for an independent investigation into Russian interference in the U.S. election, regardless of who takes up the post of director of the FBI.

Both the White House and the FBI were not immediately available for comment when contacted by CNBC.