Over the weekend, the incoming chairman of the House Judiciary Committee, Rep. Jerry Nadler, made his views on President Donald Trump’s recent appointee for acting attorney general, Matthew Whitaker, clear. “He’s totally unqualified,” Nadler said. “And his only qualification seems to be that he wants to be—that the president wants him to be the hatchet man to destroy the Mueller investigation.”

Given what the president and Whitaker have stated publicly about special counsel Robert Mueller’s probe into Russian interference in the 2016 election, this “hatchet man” designation might be spot-on. Whitaker has both prejudged the investigation as having failed to produce evidence of collusion and obstruction of justice and laid out what he called a “crafty” approach to kill the probe by starving it of funding.

These are a few of the ways Whitaker could attempt to sabotage the probe if he doesn’t recuse himself from overseeing the special counsel. Whitaker has the power to bar Mueller from publicly releasing his report on possible presidential malfeasance or sending the document to Capitol Hill for lawmakers to review. He could even attempt to water that report down. He would also be able to approve or deny Mueller’s major prosecutorial decisions, such as future indictments and cooperation deals.

Newly empowered Democrats, meanwhile, have promised to protect Mueller from being arbitrarily fired or otherwise interfered with in the event that Whitaker does not recuse himself. But say, in the months before Democrats take office in January, Whitaker issues Mueller what he views as an obstructive order, which Mueller then ignores, and Whitaker fires him. How could Democrats protect Mueller then? Could they go so far as to rehire the former FBI director and his team to finish their work, for example? The answer is: Yes, they could do a version of that.

The House could vote to create a “Special Select Committee on Russian Election Interference” and put Mueller and his team on the case as lead investigators. Alternatively, lawmakers could simply subpoena Mueller’s work product and hire him to complete any unfinished report with whatever material he already has.

House Democrats are unlikely to want to let Trump get away with firing Robert Mueller and ending his investigation when they now have the power to stop him.

Indeed, the only thing that might prevent an appointment of Mueller to helm a congressional investigation along the lines of the current Russia probe would be Mueller’s own reluctance to take that job.

If he did take the position, though, there would be a critical constraint on Mueller’s power: He would no longer be able to seek indictments from a grand jury. Mueller has secured more than two dozen indictments so far, winning a number of high-profile convictions and guilty pleas against a number of the president’s former top aides. This approach has resulted in cooperation deals with former national security adviser Michael Flynn, former campaign adviser George Papadopoulos, former Trump campaign chairman Paul Manafort, and deputy chairman of Donald Trump’s inaugural committee Rick Gates. Without the ability to issue new indictments, a Mueller commission will not have as much ability to turn the pressure up on potential cooperators.

There are those subpoenas, though, which Mueller could request and a Democratic-led committee could approve. Under such a scenario, he could continue to seek document production and testimony from key witnesses using the committee-approved subpoenas. His current subpoena power is generally considered to be broad—having defeated long-shot legal challenges, few witnesses have actually resisted him. Any new Congress-based subpoena power, though, would come with a set of obstacles Mueller will not have previously faced if obstinate Trump officials, former officials, and affiliates were to attempt to ignore the documents.

Like a court, Congress is able to enforce its subpoena power by holding violators in contempt. Doing this requires a mere majority vote of the entire House of Representatives. Bush White House counsel Harriet Miers and Obama Attorney General Eric Holder, for example, were held in contempt by respective opposing House majorities in recent years. You probably don’t recall seeing either Miers or Holder being frog-marched to prison. That’s because, for the past century, the enforcement mechanism for congressional contempt has been criminal proceedings pursued through the Justice Department, which has a policy of not prosecuting congressional contempt when witnesses cite executive privilege. It seems unlikely that a Trump DOJ—particularly one that would fire Mueller—would change that policy. Indeed, it’s possible to imagine Trump loyalists in such a department attempting to expand this policy, refusing to prosecute witnesses who reject House subpoenas regardless of executive privilege claims. As law professor Steve Vladeck has written, “It’s not hard to imagine a scenario in which this Justice Department would be in no particular hurry to prosecute executive branch officials who, at the president’s insistence, have defied congressional subpoenas—perhaps even after the courts have rejected the grounds on which the subpoenas were defied..”

Still, contempt of Congress proceedings could end up in court, where Democrats might get a more favorable outcome, such as a court issuing heavy fines or jail sentences. This hasn’t been tested before, because when these types of proceedings were initiated in past administrations, the issues involved were eventually made moot for two main reasons. First, congressional contempt citations expire after a term of Congress is up. Second, because these citations come with a clock, courts have never been forced to decide how to enforce them.

Courts have consistently maintained, though, in recent rulings that contempt disputes between the executive and legislative branches of government are justiciable by the third branch. While the judiciary has maintained its constitutional role in resolving these disputes, it has generally sought and received settlements between the other two branches without having to enforce anything. If there were a Mueller firing followed by a wholesale rejection of congressional subpoena power by witnesses in a House Russia probe, courts would almost certainly be asked to act with greater urgency. “If Trump administration officials invoke privilege claims to defy subpoenas, the courts would be asked to resolve whether those claims are valid,” Vladeck wrote. “But while President Trump may think the odds are in his favor at that point, the court has, historically, generally recognized a broad congressional subpoena power—and limited presidential authority to resist otherwise valid subpoenas. In other words, it’s not necessarily a given that even judges and justices appointed by Trump would side with him in such a case.”

Even if this constitutional crisis were too slow-moving, there could be a last-ditch political remedy for House Democrats, short of impeachment. For most of the country’s history, Congress enforced its own contempt citations through what’s known as the “inherent contempt” power that can come with a majority of one House of Congress holding an uncooperative witness in contempt. Congress has never used that power to levy fines, but it might be able to, according to a Congressional Research Service study, which observed that multiple Supreme Court opinions from the early years of the republic indicated that the 19th-century court viewed contempt fines to be within Congress’ powers.

What the court definitively viewed to be within Congress’ powers was jailing witnesses who disobeyed congressional subpoenas. For most the 19th century and part of the 20th, either branch of Congress could issue a majority vote to order the sergeant-at-arms to arrest and imprison recalcitrant witnesses. Again, this used to be fairly standard practice—Congress even had its own prison, the Old Capitol Jail. But the Old Capitol Jail was sold not long after the Civil War and demolished in the first half of the 20th century. The last time Congress actually exercised its power to arrest people was in 1935, with the legislature opting to utilize an 1857 law that allowed it to refer contempt citations to the Department of Justice for criminal prosecutions. It’s unlikely that Nancy Pelosi wants to be remembered as the House Speaker who brought back the practice of hauling in recalcitrant witnesses to be jailed by the House’s sergeant-at-arms on the orders of a vote by the Democratic Caucus. There would certainly be the potential for a political uproar if we were to see Donald Trump Jr. in cuffs based on a vote by his father’s opposition party.

Even so, House Democrats are similarly unlikely to want to let Trump get away with firing Robert Mueller and ending his investigation when they now have the power to stop him.