As acting Attorney General Matthew Whitaker's refusal to recuse himself from overseeing the Mueller probe rattles Democrats and even Kellyanne Conway's husband - all of whom worry that President Trump may finally have found a way to force an ending to the interminable investigation - the shortlist for Jeff Sessions' replacement is growing longer.

According to multiple media reports, Trump is considering no fewer than seven people for the job: Chris Christie, Rudy Giuliani, former Florida Attorney General Pam Bondi, Labor Secretary Alex (not Jim) Acosta, HHS Secretary Alex Azar, US Appeals Court Judge Edith Jones and former Attorney General William Barr, who held the job under President George W Bush.

South Carolina Senator Lindsey Graham has also been rumored as a top pick, and is far and away the leading candidate on online betting markets, though his name has been largely absent from media reports.

Alex Acosta

To that list, some would add Whitaker, who has remained a favorite to remain in the job permanently despite being a politically contentious pick. But according to Bloomberg, members of the GOP's senate leadership are pushing for Acosta, seeing him as more likely to win confirmation given that he has already been vetted and has a more compelling life story. Acosta, the son of Cuban refugees, went to Harvard for undergrad and law school before clerking for the Supreme Court.

Causing no end of frustration for Democratic leaders, Whitaker has so far refused to recuse himself from overseeing the Mueller probe, despite his public criticism of Mueller's probe as illegal and a "witch hunt." And sources close to Whitaker say he has no intention of doing so (and why would he, considering that would almost certainly sink any chance he has of staying in the job). However, Whitaker has reportedly told friends that he would consult Justice Department ethics officials if a specific conflict arose.

Pam Bondi

Anyone who takes the reins of the Mueller probe will have the option of dismissing an agreement between Deputy AG Rod Rosenstein and Mueller that gave Mueller a long leash, which he has used to expand the investigation far beyond its original scope of examining links between the Trump Campaign and the Russian government. Democratic leaders, including Chuck Schumer and Nancy Pelosi, have said that the timing of Sessions' firing is "suspicious" given that Democrats are expected to leverage their subpoena power to open even more investigations into Trump on everything from his personal finances, to his Russia ties. Pelosi and Schumer have demanded that Congress take immediate action to protect Mueller.

It is impossible to read Attorney General Sessions’ firing as anything other than another blatant attempt by @realDonaldTrump to undermine & end Special Counsel Mueller’s investigation. — Nancy Pelosi (@NancyPelosi) November 7, 2018

Given his record of threats to undermine & weaken the Russia investigation, Matthew Whitaker should recuse himself from any involvement in Mueller’s investigation. Congress must take immediate action to protect the rule of law and integrity of the investigation. #FollowTheFacts — Nancy Pelosi (@NancyPelosi) November 7, 2018

Even one Republican Senator said she's "worried" that Mueller won't be allowed to finish his work.

It is imperative that the Administration not impede the Mueller investigation. I’m concerned Rod Rosenstein will no longer be overseeing the probe. Special Counsel Mueller must be allowed to complete his work without interference—regardless of who is AG. — Sen. Susan Collins (@SenatorCollins) November 7, 2018

One Bloomberg source questioned whether Christie and Bondi, both politically divisive figures, could win Senate confirmation.

But the whims of any future AG pick may not be the biggest threat to the Mueller probe. A court challenge to Mueller's authority has taken on new significance in light of recent events, according to Reuters.

A DOJ attorney on Thursday spelled out the circumstances under which Special Counsel Robert Mueller could be fired in a court case that took on new significance this week following Sessions' ouster. After refusing to comply with a Mueller grand jury subpoena back in May, Roger Stone associate Andrew Miller filed a court challenge alleging that Mueller's authority was illegitimate because he was illegally appointed. That case is being argued on Mueller's behalf by Deputy Solicitor General Michael Dreeben.

Here's more from Reuters.

In May, Andrew Miller, who is an associate of long-time Trump adviser Roger Stone, refused to comply with a grand jury subpoena from Mueller. Miller was held in civil contempt. He filed a legal challenge, asserting Mueller has no authority to compel his testimony or to oversee the probe because he was illegally appointed. Dreeben told a three-judge appeals panel on Thursday that there are checks and balances on Mueller’s activities that make his appointment lawful. One of these is that he could be fired by Whitaker, now acting attorney general, if Whitaker revoked department regulations governing Mueller’s appointment to make him fireable without cause. The special counsel is not "off in a free-floating environment," Dreeben said in arguments before the U.S. Court of Appeals for the District of Columbia Circuit that attempted to show Mueller’s power is circumscribed by the law.

It's unclear when a ruling might be handed down in that case. But, until it is resolved, lawmakers and President Trump will be eagerly watching to see if the court might simply eliminate one of the president's most enduring headaches without the president having to do a thing - or expend any of the precious political capital that, in an era of divided government, will be in increasingly short supply.