We already know that voters have grown tired of the special-counsel melodrama, but voters don’t have much impact on investigations. According to Politico, however, Robert Mueller may be losing some of his political cover with Republicans on Capitol Hill. The “wrap it up” chorus has grown both louder and larger, and that might have some consequences for Mueller’s credibility when the probe finally does finish:

Republican Sen. John Thune says special counsel Robert Mueller should “start winding this down.” Speaker Paul Ryan says “we want to see this thing come to its conclusion.” And House Majority Whip Steve Scalise says he fears Mueller’s probe is “becoming a witch hunt.”

A growing number of Republicans in senior leadership positions, who all profess that Mueller should have no artificial deadline for his Russia influence probe, have also begun to sprinkle in another suggestion: It’s time to wrap it up.

The message is a nod to the gravitational pull of President Donald Trump and his most vocal allies in Congress, a band of hardcore Mueller critics who have made moves to choke off his funding and encourage him to wrap up immediately. Though most senior GOP lawmakers say Mueller should let the facts dictate his probe, their willingness to embrace the hurry-up language is a sign of increasing pressure and division among Republicans about the party’s posture toward the investigation as it enters a perilous phase for Trump and his allies.

“Wrap it up” has become the message of choice for lawmakers trying to straddle the line. Sen. Mike Lee (R-Utah) sent the message shortly after Thune spoke to Fox News, telling CNN that “I’d like to see them wrap it up.” And the GOP’s Missouri Senate nominee, Josh Hawley, followed suit last week in urging Mueller to “wrap it up and present his evidence.”

Has this chorus grown in response to voter impatience, or the other way around? It’s a chicken-egg question that’s largely academic. The practical impact of both is that the longer this drags out, especially without any indictments on the core of the probe (hypothesized Russian collusion) other than process crimes, the less credibility the hypothesis has. This isn’t exactly an administration that’s great at keeping secrets, after all, and it’s reasonable to ask whether there’s anything to find after more than a year of looking. The growing “wrap it up” chorus highlights that lack of success and suggests that Mueller might be stretching it out to manufacture a case that simply doesn’t exist. It won’t be much longer before some of the same Republicans start suggesting that sotto voce … at first.

Mueller has another problem in credibility. Tomorrow’s release of the inspector general report on the Hillary Clinton investigation is likely to damage the reputations of senior FBI and Department of Justice officials that participated in the Trump-Russia probe and/or will be needed for testimony at some point in it, assuming anything comes of the probe at all. Michael Horowitz’ continuing probe of the conduct of these officials and others in the Russia-collusion probe could cause even more damage to any court case Mueller tries to prosecute. The sands of those particular hourglasses are draining away relentlessly too, and might leave Mueller with nothing more than a set of unprovable theories if Horowitz finds enough wrongdoing to block the use of evidence in court.

The longer this goes, the worse those conditions become for Mueller. He needs to wrap things up for the sake of his own mission, notwithstanding the politics surrounding the investigation.