Appointing a special prosecutor after Comey firing could be 'problematic,' expert says ABC News' Dan Abrams said appointing a special prosecutor is unlikely.

 -- Democratic lawmakers are demanding the appointment of a special prosecutor to investigate Russian interference in the 2016 U.S. election after FBI Director James Comey was fired on Tuesday.

Senate Minority Leader Chuck Schumer, D-N.Y., reacted to Comey’s termination on Twitter Tuesday night, writing, “If we don’t get a special prosecutor, every American will rightfully suspect that the decision to fire #Comey was part of a cover-up.”

Sen. Cory Booker, D-N.J., posted a video statement on Twitter: “Now, as much as ever, we need an independent special counsel to investigate Russian interference in our elections.”

Sen. Jeff Merkley, D-Ore., tweeted a similar reaction, saying, “In case the need for an independent special prosecutor to investigate the #TrumpRussia ties wasn’t clear enough already … it sure is now.”

In an interview today on “Good Morning America,” Sen. Tim Kaine, D-Va., told ABC News chief anchor George Stephanopoulos, “We need a special prosecutor.”

But ABC News chief legal analyst Dan Abrams said appointing a special prosecutor is unlikely and could be problematic.

“The problem there is that, typically, a special prosecutor would be appointed by the attorney general [Jeff Sessions]. In this case, that’s not going to happen. [Sessions] may say he’s even recused from that decision,” Abrams told Stephanopoulos and co-anchor Robin Roberts on “GMA” this morning.

“Then it goes to the deputy attorney general. It’s pretty clear the deputy attorney general isn’t going to order a special prosecutor,” Abrams continued. “So then the question becomes, can Congress put enough pressure on the administration to appoint a special counsel? And that’s going to be a political decision.”

“It seems unlikely at this point that something like that’s going to happen,” he added. “But that’s the way it would occur.

The White House released the letter that President Donald Trump wrote directly to Comey, which said his termination was “effective immediately” and cited recommendations of the United States attorney general and the deputy attorney general.

Two FBI sources told ABC News that Comey's termination was read to him over the phone while he was traveling for the bureau in Los Angeles. A separate FBI official told ABC News that Comey first learned of his firing by seeing news reports on TV. The official said Comey was "surprised, really surprised" and was "caught flat-footed."

Comey's dismissal came just weeks after he testified in front of the House Committee on Intelligence, during which he took the rare step of confirming that the FBI was investigating alleged Russian interference in the 2016 U.S. presidential election and "any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia's efforts."

ABC News' Riley Beggin, Jack Date, Justin Fishel, Jonathan Karl, Meghan Keneally and Alex Stone contributed to this report.