Texas Sen. John Cornyn took to Twitter over the weekend and, as TPM's Christina Cabrera explained, joined "the growing chorus of Republicans that have been casting doubt on the legitimacy of Special Counsel Robert Mueller’s Russia probe."

Former Attorney General Eric Holder tweeted on Friday, “Speaking on behalf of the vast majority of the American people, Republicans in Congress be forewarned: any attempt to remove Bob Mueller will not be tolerated.”

Cornyn retweeted Holder and simply added “You don’t,” suggesting that he may very well be open to the idea of removing the special counsel.

When Bloomberg’s Steven Dennis tweeted on Saturday that “[Cornyn]’s beef is with Holder, not Mueller,” Cornyn responded with “But Mueller needs to clean house of partisans.”

“Will you accept the findings of the Mueller probe as legitimate, @JohnCornyn?” asked Washington Post reporter Greg Sargent.

“Makes sense to me to wait to see what they are first,” Cornyn said.https://twitter.com/JohnCornyn/status/942118407486496769

These tweets from the Senate’s second top Republican reflect the GOP’s efforts to discredit Mueller and his investigation into President Donald Trump’s election campaign, which accelerated this week when the Justice Department released anti-Trump texts from an FBI agent who had been on Mueller’s team.

Republicans pounced on the texts, echoing Trump’s repeated talking points that Mueller was biased.

Cornyn was asked about the exchange on ABC's This Week by host George Stephanopoulos. Cornyn told Stephanopoulos he did have confidence in Mueller and that it would be a "mistake" for Trump to fire him, but was not asked what he or his fellow Republicans would do if the rumors are true and Trump tries go get rid of him before the month is over.

STEPHANOPOULOS: One of the other X-factors heading into 2018, of course, is the Russia investigation led by special counsel Robert Mueller. You have been active on Twitter over the weekend responding to the former attorney general, Eric Holder. In one of your tweets you said that Mueller needs to clean house of partisans. And then you were asked in another tweet, will you accept the findings in the Mueller probe as legitimate by Greg Sargent of The Washington Post.

You say that "makes sense to me to wait and see what they are first." That sounds like you're saying that you're going to believe that Mueller's conclusions are legitimate only if you like them.

CORNYN: Well, no, that's not true. I have a lot of admiration and respect for Director Mueller. But I would think he would want to eliminate challenges to the integrity of his investigation by eliminating agents who have taken positions either in text messages or through their political activity that undermine the integrity of...

(CROSSTALK)

STEPHANOPOULOS: Well, those people have been taken off the investigation.

CORNYN: … the results of the investigation. So I think he should want to do that because not only is an objective investigation and justice needs to be done, the appearance of justice needs to be done. And I think these conflicts of interest jeopardize the integrity of his investigation.

STEPHANOPOULOS: The FBI agent who was engaged in those text messages, both of them have been taking off the investigation. They were taken off apparently as soon as special counsel Mueller found out about them.

CORNYN: And I commend him for that. He should. And but there ought to be -- there are others who -- he needs to make sure he vets that team. There are plenty of FBI agents and prosecutors who have not been politically involved on behalf of Democrats or overtly critical of the president that can serve in this important investigation.

So I have confidence in Director Mueller. I would just think he would be concerned about the appearance of conflicts of interest that would undermine the integrity of the investigation.

STEPHANOPOULOS: It appears that some of the president's allies in the congress are starting to lay the groundwork for him to fire Robert Mueller. What would that mean if the president fired the special counsel?

CORNYN: Well, I read that the president's own lawyer says that's not going to happen. I think that would be a mistake myself.

If Trump does fire Mueller, Cornyn and his fellow Republicans aren't going to lift a finger to keep him in check. They haven't done anything about his lawlessness so far, so there's no reason to believe any of them are capable of policing themselves.