Someone needs to tell House Intelligence Committee Chair Devin Nunes to stop digging.

Nunes has faced sustained criticism for a bombshell announcement last Wednesday that an unnamed source had given him information that seemed to validate Donald Trump’s baseless wiretapping allegations. Nunes later acknowledged he had no such evidence and apologized for personally briefing top White House officials about the supposed information before speaking to the rest of his committee.

On Monday, the saga got even stranger — and the Democratic leaders of the House and Senate bluntly said that Nunes couldn’t be trusted to lead the congressional investigation into Russia’s interference in the 2016 elections. Senate Minority Leader Chuck Schumer called for Nunes to be removed from his post, while House Minority Leader Nancy Pelosi, joined by Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, said Nunes should fully recuse himself from the probe.

"The chair of the House Intelligence [Commitee] has a serious responsibility to the Congress and to the country," Pelosi said in a statement to CNN Monday evening. "Chairman Nunes's discredited behavior has tarnished that office. [House] Speaker [Paul] Ryan must insist that Chairman Nunes at least recuse himself from the Trump-Russia investigation immediately. That leadership is long overdue."

As of late Monday night, a spokeswoman for Ryan said the embattled House speaker was still standing by Nunes, a seven-term Republican congressman who was a member of the Trump transition team, and would not ask that he recuse himself. But as every new twist of the Trump wiretapping scandal has shown, that type of assurance can quickly change.

Things had begun to go off the rails for Nunes Monday morning after a strange statement from his spokesperson, Jack Langer. In the release, Langer acknowledged that Nunes paid an unannounced visit to the White House complex one day before personally telling Tump — and then the American public — that there were indications US spies had picked up communications involving Trump transition aides:

Chairman Nunes met with his source at the White House grounds in order to have proximity to a secure location where he could view the information provided by the source. The Chairman is extremely concerned by the possible improper unmasking of names of U.S. citizens, and he began looking into this issue even before President Trump tweeted his assertion that the White House had been wiretapped.

There were three eyebrow-raising things that in that quote. First, Trump’s wiretapping charge was about Trump Tower, not the White House (a point Langer later corrected). Second, Nunes has access to a highly secure facility on Capitol Hill, so there would be no reason for him to head to the White House to safely view the source’s purported evidence. Finally, the wording raises an obvious question: Did Nunes go to the White House because the source was a member of the Trump administration?

Nunes added to the confusion during an interview with CNN later on Monday when he took pains to say he’d visited the White House grounds, but not the White House itself, and that he didn’t believe Trump or top West Wing staffers even knew he was there. That seemed highly unlikely, since Nunes would have needed to be cleared into the complex — meaning that at least one senior White House staffer knew he was coming.

Democrats in both the House and Senate spent the day arguing that Nunes had shown himself to be incapable of leading an impartial investigation. Democrat Rep. Jim Himes of Connecticut told CNN that Nunes’s actions were “bizarre” and “loopy,” while Senate Majority Leader Chuck Schumer urged House Speaker Paul Ryan to remove Nunes from his post on the intelligence panel.

"Chairman Nunes is falling down on the job and seems to be more interested in protecting the president than in seeking the truth,” Schumer said. “You cannot have the person in charge of an impartial investigation be partial to one side. It's an inherent contradiction.”

The sharpest dagger came from Schiff, the top Democrat on the House intelligence panel. A normally mild-mannered lawmaker, Schiff had worked hard in recent days to maintain a veneer of bipartisanship when it came to Nunes and the Trump wiretapping probe. That fell away Monday night, revealing a stark political divide about the future of the probe — and about Nunes’s integrity and credibility.

"We've reached the point, after the events of this week, where it would be very difficult to maintain the credibility of the investigation if the chairman did not recuse himself from matters involving either the Trump campaign or the Trump transition team of which he was a member," Schiff told CNN.

One thing is clear: Nunes has spent more than a week trying to deflect attention from the FBI’s bombshell announcement that it is formally investigating the Trump campaign’s ties to Russia, but he’s actually been making Trump’s Russia problem even worse.

That’s bad news for Trump, but it’s even worse news for an ambitious lawmaker getting his first time on the national stage — and making so many missteps that he’s now facing criticism from fellow Republicans, calls that he be replaced as head of the intelligence committee, and growing pressure for an independent probe that would bypass his committee entirely.

The head of the Trump-Russia probe is mouthing nonsense

To understand what’s been going on, rewind the clock to last Monday, when FBI Director James Comey confirmed for the first time that the bureau was conducting a criminal investigation into “any links between individuals associated with the Trump campaign and the Russian government” and into “whether there was any coordination between the campaign and Russia’s efforts.”

Comey — joined by Adm. Mike Rogers, the head of the National Security Agency — also shot down Trump’s allegation that then-President Barack Obama tapped his communications during the campaign. Both men flatly said there was no evidence to support Trump’s claim, which had also been refuted by top lawmakers from both parties.

Enter Nunes, whose committee is meant to be overseeing the congressional investigation into Team Trump’s possible Russian ties. On Wednesday, he told reporters that an unnamed source had informed him that US spies had surveilled the Trump administration’s transition team. He also acknowledged going to the White House to brief top officials there before talking to Democratic members of the committee.

Nunes provided no evidence to bolster Trump’s initial accusations, and over the course of the week he started to hedge and walk back the claim that he’d information that supported any part of the president’s allegations. By Friday morning he was saying that he couldn’t be sure that Trump’s or his aides’ conversations were captured by surveillance at all. Nunes also apologized to fellow members of the House Intelligence Committee for going to the White House in the first place.

But that wasn’t the end of Nunes’s Russia stumbles. On Friday, he infuriated Democrats anew by abruptly canceling a planned public hearing with top former national security officials about Russian interference in the 2016 election. The House panel was originally scheduled to hear from President Obama’s former Director of National Intelligence James Clapper, former CIA Director John Brennan, and former acting Attorney General Sally Yates on Tuesday.

The cancellation sparked a strong response from Schiff, the top Democrat on the committee, who took to Twitter to slam the move as an “attempt to choke off public info.” On Monday, Schiff, said Nunes should recuse himself from any further role in the investigation.

Arizona Republican Sen. John McCain cited Nunes’s actions when he renewed his calls for a specially appointed and nonpartisan select committee to take over the Trump-Russia investigation from Congress: "No longer does the Congress have credibility to handle this alone, and I don't say that lightly," he said.

Some mainstream conservative media figures, like Morning Joe host Joe Scarborough, had an even stronger reaction than McCain. “If the Republican Party wants to do what is best for this country and its national security, they will remove Devin Nunes as Intel Chairman,” Scarborough tweeted.

In a blistering editorial, meanwhile, the New York Times said Nunes had “destroyed the credibility of his committee” and “[made] clear that he is unfit for the job and should be replaced.”

As my colleague Zack Beauchamp noted, sacrificing his credibility with Democrats and the Republican mainstream on the comparatively minor issue of Trump Tower surveillance means that Nunes has managed to create pressure to take the much more important investigation into Trump’s Russia ties out of his hands.

That’s bad news for Trump. In the short term, though, it’s even worse news for Nunes.