For starters, the election in Alabama is already underway. Absentee ballots are being mailed in for the Dec. 12 contest, and Moore can't be removed from the ballot, even if the Alabama Republican Party wanted to.
A victory by Democrat Doug Jones would narrow the margin of control in the GOP-controlled Senate to 51-49. That's an outcome Republicans are anxious to avoid.
One way, albeit difficult, for Republicans to retain the seat would be to mount a successful write-in candidacy. Several Republican senators are urging Sen. Luther Strange, who lost to Moore in the GOP primary in September, to launch such an effort.
But Strange said Monday, "I think, right now, a write-in candidacy is highly unlikely."
If Moore were to win, there's no precedent in the Senate for refusing to seat him. But the Senate could immediately move to expel him, though the chamber hasn't taken such a step since the Civil War.
Moore remains defiant and retains a base of supporters in staunchly conservative Alabama. He says allegations that hewhen he was a prosecutor in his 30s are false and the product of a witch hunt.
The Senate's options for dealing with Moore:
One option under consideration would be for Republicans in Alabama to abandon Moore and rally around a write-in candidate, perhaps Strange or even U.S. Attorney General Jeff Sessions, who held the seat until his confirmation earlier this year. Such a candidacy would be an uphill slog, particularly if Moore remains defiant and pulls a sizable vote from his impassioned base of evangelical supporters.
Even if Moore were to step aside his name would remain on the ballot — siphoning votes away from any write-in candidate — and potentially swinging the race to Jones.
chairman of the Senate GOP's campaign committee, said on Monday that even if Moore were to win the election, the Senate might move to expel him. If that were to occur, GOP Gov. Kay Ivey would appoint another interim senator.
The U.S. Constitution says that both House and Senate have the power to "punish its members for disorderly behavior, and, with the concurrence of two-thirds, expel a member." The Senate has expelled 15 of its members, 14 of whom were supporters of the Confederacy, but hasn't expelled anyone since 1862. More recently, members such as Bob Packwood, the Oregon Republican who faced charges of sexual misconduct and abuse of power, have resigned rather than face expulsion.
In theory, expulsion offers a long-shot path for establishment Republicans to reclaim the seat. But Moore would have to win the seat in the first place, and do so in the face of a potential write-in candidacy and opposition from state and national Republicans.
"It's premature to talk about expelling someone who hasn't been elected," said No. 2 Senate Republican John Cornyn of Texas.