Ultra-conservative Congressman Mo Brooks (R-AL) took a big step in the right direction by insisting that Donald Trump's replacement for fired FBI Director James Comey needs to be someone on whom Democrats and Republicans can agree. And he threatened congressional action on a special prosecutor if that doesn't happen.

It is only day three of the constitutional crisis that Donald Trump created when he fired FBI Director James Comey, the man charged with investigating possible collusion between Trump’s team and Russia, and there are already important signs that Republicans may abandon Trump over the move.

While some moderate Republicans in the House (and very few in the Senate) have expressed conditional support for an independent investigation and/or a special prosecutor since Comey’s firing, one ultra-conservative member of the House has stepped up with some very strong language on the subject.

Readers of Shareblue are well aware that Rep. Mo Brooks (R-AL) is no moderate, to say the least, but even he recognizes the inherent conflict that the Comey firing poses. In an interview with MSNBC’s Chris Hayes, Brooks said that Trump’s replacement had “better be” someone Democrats have confidence in, voicing conditional but strong support for a special prosecutor to conduct an independent probe, should that not be the case:

BROOKS: We cannot continue to have this kind of politicization of the FBI, and I think we need to wait and see who the president is going to nominate to fill that position. But it better be somebody that the Democrats and the Republicans both have confidence in.

HAYES: Right.

BROOKS: And it needs to be somebody who, as best as possible in this heated environment, will eliminate the partisan politics that seems to have permeated the top of the FBI to some degree. Now, if the president nominates somebody who does not fit that mold, then we have to start looking at whether it is appropriate to appoint a special investigator or prosecutor or whatever you want to call this person, so that we can confidence in the investigation that you referenced.

Brooks went on to say that Trump “has to go overboard in appointing someone as the new FBI director that the Democrats are comfortable with,” and if Trump doesn’t, “Congress may have to step in to appoint a special investigator or prosecutor.”

Brooks’ grant of the benefit of the doubt to Trump is far too generous, but the fact that he is prepared to make such unequivocal demands, and to promise not just to support, but to potentially demand, a special prosecutor if Trump fails to find a replacement that’s suitable to Democrats, is huge.

Brooks’ influence may be narrow, but his stance bodes poorly for Trump. If Trump tries to appoint someone like Rudy Giuliani or Chris Christie, it stands to reason that many more Republicans will join Brooks in demanding a special prosecutor.