Comey affair: What comes next?

US President Donald Trump's surprising move to fire the head of the Federal Bureau of Investigation (FBI), James Comey, sent resounding shockwaves throughout the US capital.

Trump said the decision was based on Comey's handling of the Hillary Clinton email probe, but critics said they believe the real reason was the FBI's investigation into Russia's alleged meddling in the 2016 election to Trump's benefit and possible Russian ties to officials in Trump's campaign.

The next order of business in Washington will be naming an interim FBI head while the White House searches for a permanent replacement. While the process is sure to be politically charged, Trump's Republicans enjoy a razor-slim majority in the Senate, where the president's candidate will require a simple majority to enter office.

Some Democrats have suggested that they would oppose Trump's FBI chief nominee if the White House refuses to allow an independent special prosecutor to investigate alleged Russian meddling in the election.

"I would oppose confirmation of a new FBI director until there is support for a special prosecutor," Democratic Senator Richard Blumenthal told reporters on Wednesday.

Senate Minority Leader Chuck Schumer wrote on Twitter that the Democrats "demand" the appointment of a special prosecutor.

Democrats said they are concerned that the Russia investigation will now be conducted by a hand-picked Trump ally, which they said could compromise the probe.

Who will be the new FBI head?

Although the White House hasn't named any potential candidate to serve as the new FBI director, US media reports have honed in on several possible picks:

Where does this leave the Russia investigation?

The investigation is still on-going and Comey's departure does not change that. The question is who will now hold the reins.

As it is a part of the US Justice Department, the FBI's investigation is currently being overseen by Deputy Attorney General Rod Rosenstein. Attorney General Jeff Sessions recused himself from the investigation after it was revealed that he had his own contacts with Russia's ambassador in Washington.

There are also oversight investigations being pursued by the Senate and House intelligence committees. The committees, however, cannot bring criminal charges and are not privy to the same information as an FBI investigation. Their results can be issued in classified and public reports.

Why did Trump fire Comey?

Since dismissing Comey, Trump has stood by his rationale for the sacking, saying Comey "was not doing a good job" with the Clinton email probe. Sources speaking anonymously to US media told a very different story than the one coming from the White House.

The New York Times, CNN and the Washington Post all reported that shortly before Comey was fired, he requested additional funding and personnel for the FBI's Russia probe. 

Some 30 officials from the White House, the Justice Department, the FBI and senior Republicans, told the Washington Post that Trump was angry with Comey for paying more attention to the Russia investigation and not inspecting leaks of White House policies to journalists.

Could Trump really be impeached over this?

The short answer? Not based on what is currently known about Russia's alleged role in manipulating the US election and not in the current US political landscape.

The long answer? Some observers have said Comey's dismissal could potentially be seen as an abuse of office - an impeachable offense - if Trump fired Comey to stop the investigations against himself and members of his campaign and administration. 

Removing the president for committing an impeachable offense is a two-step process. First at least half of the lawmakers in the House of Representatives would have to vote to impeach the president, then after hearing evidence, at least two-thirds of the Senate would have to decide to convict the president and thus remove him from office.

While a case could possibly be made for Trump's impeachment on possible obstruction of justice charges over Comey's firing, there isn't enough credible evidence yet to prove it. Furthermore, Republicans in Congress do not seem interested in pursuing any investigation.

Although some Republicans have questioned the timing of Trump's decision, there is no indication that they would turn on the president in the number required for impeachment. The Republican Party enjoys majorities in both houses of the US Congress; so there is no chance Democrats could remove the president from office without Republican support.

The day after Comey's firing, Vice President Mike Pence said Trump "made the right decision at the right time." Similarly, leading Republicans including House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell also firmly stood behind Trump's decision.

McConnell also dismissed calls on Wednesday for a special prosecutor to be brought in on the Russia campaign, saying it "could only serve to impede the current work being done" by the FBI and the Senate intelligence committee.

Maximiliane Koschyk contributed reporting.