On Wednesday, Deputy Attorney General Rod Rosenstein will appear before a highly partisan, bitterly divided House Judiciary Committee, and the stakes couldn’t be higher. He’s been summoned by Republicans, mostly allies of President Trump, and it’s expected that Rosenstein will be raked over the coals by the committee’s GOP members, some of whom are likely to push him to wind down the investigation led by Robert Mueller, the Russiagate special counsel—or even to shut it down entirely.

Because Attorney General Jeff Sessions has recused himself from the Russia inquiry, thanks to his own entanglement in it, Rosenstein, the Justice Department’s number-two official, is the one overseeing Mueller’s office. So it’s Rosenstein who has the power to fire him. Even though Rosenstein, who appointed Mueller in the first place, has said repeatedly—including last week—that he’s satisfied with Mueller’s work so far, the committee’s GOP hard-liners apparently intend to create a circus-like atmosphere that will provide cover for the president, if and when he decides it’s time to get rid of the special counsel. Those hard-liners include Representatives Matt Gaetz of Florida, Jim Jordan of Ohio, and Andy Biggs of Arizona; Gaetz has gone so far as to warn that Mueller’s actions could amount to a “coup d’état” against the White House.

Appearing before the Judiciary Committee last week, FBI Director Christopher Wray—appointed to succeed James Comey, who was fired by Trump over, as the president put it in his May interview with NBC’s Lester Holt, “this Russia thing with Trump and Russia”—was blasted by Republican after Republican, who questioned him about alleged prejudicial behavior and wrongdoing by Mueller. Said Bob Goodlatte, the Virginia Republican who chairs the committee, “We do not know the magnitude of insider bias on Mr. Mueller’s team.” (Meanwhile, Goodlatte is pushing for the appointment of a second special counsel, this one charged with investigating the Clintons.) In a classic example of GOP whataboutism, other members of the committee demanding that the FBI ought to be investigating Hillary Clinton rather than Trump, echoing Trump’s own intemperate tweet: “After years of Comey, with the phony and dishonest Clinton investigation (and more), running the FBI, its reputation is in Tatters—worst in History!”

There’s no doubt that Trump is readying his counterattack against both Mueller and the FBI, and his allies are egging him on. The erratic president could order the firing of Mueller, close down or defund the Office of the Special Counsel, or pardon those already indicted or in Mueller’s crosshairs. Any of those actions would be guaranteed to provoke a political firestorm and generate serious considerations of impeachment, even among some GOP members of Congress. Trump’s lawyers, no doubt, are counseling him to be patient. But, for the White House, the Mueller investigation has struck at the heart of Team Trump via its December 1 plea agreement with Gen. Michael Flynn. It’s looking like the next target could be Trump’s son-in-law, Jared Kushner.

In other words, a dangerous political showdown could be in the offing. And it isn’t clear if the country can handle it. “Firing Mueller would cause a severe political upheaval,” Representative Eric Swalwell, a Democrat who serves on the House Permanent Select Committee on Intelligence (HPSCI), told The Nation. “It would create a constitutional crisis. And I believe it would be a clear case of obstruction of justice.”

Of course, firing Mueller isn’t as easy it might seem. The president can’t do it directly; instead, he’d have to instruct Rosenstein to do the deed. But Rosenstein would probably refuse such an order, choosing to resign rather than comply. Then, in a Saturday Night Massacre–like sequence, the president would have to work his way down the Justice Department’s line of succession until he found a department officer willing to oust Mueller. This could prompt an ugly series of confrontations and resignations, explosive politically and highly damaging to the president. But Trump, whose damn-the-torpedoes instincts are well known, might already be desperate enough to risk the consequences.

Last week, Christopher Ruddy, a close friend of Trump’s who has said that he’s spoken to the president “quite a bit” about Mueller recently, said on ABC’s This Week that “Robert Mueller poses an existential threat to the Trump presidency.” Meanwhile, over at Breitbart, which has been running a nonstop series of critical reports aimed at undermining Mueller, Steve Bannon is warning the president that it’s time to get tough with the special counsel, including withholding documents that Mueller is asking for and cutting off funding for Mueller’s office. Fox’s Sean Hannity, who advises Trump, last week called Mueller “a disgrace to the American justice system [who] has put the country now on the brink of becoming a banana republic.” The Wall Street Journal, in a December 4 editorial, called on Mueller to quit.

Other Trump allies, and many Republicans in Congress, are raising a series of objections about the Office of the Special Counsel, including how much it’s spending. (In fact, not a lot, compared to, say, Kenneth Starr’s investigation of Bill Clinton. As The Guardian noted, the $3.2 million that Mueller has spent so far is about as much as the cost of one Trump trip to Mar-a-Lago.) They’ve also raised spurious questions about the alleged anti-Trump views of a couple of Mueller’s investigation team members, Andrew Weissmann and Peter Strzok, the latter of whom was reassigned by the FBI. As The Washington Post put it:

Republican activists and lawmakers are engaged in a multi-front attack on special counsel Robert S. Mueller III’s probe of possible connections between associates of President Trump and Russian agents, trying to stop or curtail the investigation as it moves further into Trump’s inner circle.

For months, the president and his allies have been seizing on any whiff of possible impropriety by Mueller’s team or the FBI to argue that the Russia probe is stacked against Trump—potentially building the political support needed to dismiss the special counsel.

Some Democrats are very worried. “It’s alarming how low the president’s supporters are willing to go, as to try to smear our premier law enforcement agency,” says Representative Swalwell. He was concerned when he read that Jeanine Pirro, a Fox News provocateur, recently met with both President Trump and his chief of staff, John Kelly, and told them that Mueller ought to be fired. Will Trump do it? “The president seems to listen most to the last person who has his ear,” Swalwell replied. “And the tone among his defenders in Congress, in the right-wing media and the president’s own words, well, it feels ominous right now.”

“The plea secured by Mueller [with Flynn] may prompt the White House and its allies to seek to curtail congressional investigations, as President Trump has attempted to do already, or end the special counsel’s work prematurely,” said Adam Schiff, the ranking Democrat on HPSCI. “Congress must make it clear that this would not be acceptable, that we will continue doing a diligent and thoughtful investigation, and do everything in our power to ensure the independence of the special counsel.” (As I reported here in August, Democrats on the Hill, joined by a handful of Republicans, have prepared legislation seeking to protect Mueller from being fired by Trump; those efforts are continuing.)

Meanwhile, when asked about reports that Trump’s lawyers believe that Mueller may be wrapping things up soon, Trump’s friend Ruddy said, “I don’t know what they’re smoking.”