Here's what happened the last time someone was expelled from the Senate, more than 150 years ago

• Republicans are floating the idea of expelling Roy Moore from the Senate, should he win the election in Alabama on December 12.
• It's a rare move that Senate rules allow for, if its body votes with a two-thirds majority.
• Expulsion hasn't actually occurred since the days of the Civil War, when the Senate voted to oust 14 members who supported the Confederacy.

---

Top Republicans have been exploring their options regarding what to do if Alabama voters next month elect Roy Moore, the GOP candidate running for Senate amid multiple allegations of sexually harassing and assaulting teenage girls.

Senate Majority Leader Mitch McConnell publicly floated the idea of mounting a write-in campaign for an alternative Republican candidate, such as Attorney General Jeff Sessions, as it's too late to replace Moore on the ballot.

But a solution that has been gaining increasing traction in recent days - as many Alabama residents staunchly maintain their support for Moore despite the allegations - is expelling Moore from the Senate should he win on December 12.

Senate rules allow for a two-thirds majority vote to remove a senator from office, which would likely mean a vote in favor from all 48 Democratic senators and 19 Republicans. At that point, the governor of the senator's state could appoint a replacement.

Even Sen. Cory Gardner of Colorado, the chairman of the National Republican Senatorial Committee, suggested the expulsion on Monday, because Moore "does not meet the ethical and moral requirements of the United States Senate."

But such a move is almost unheard of in modern politics - it hasn't successfully occurred since 1861 and 1862, when 14 senators were expelled during the Civil War for supporting the Confederacy.

After much debate about what to do with senators from states that had seceded from the Union, who had not formally withdrawn from the Senate and whose Senate terms had not expired, the Senate ultimately voted 32-10 to expel 10 absent members on July 11, 1861, according to Senate archives.

The next year, four more senators were expelled: John Breckinridge of Kentucky for taking up "arms against the Government he had sworn to support," Waldo Johnson and Trusten Polk of Missouri for "sympathy with and participation in the rebellion against the Government of the United States," and Jesse Bright for disloyalty to the Union.

Expulsion has, however, been floated as an idea several times in the last three decades, the more recent instance being in 2011, when then-Sen. John Ensign, a Nevada Republican, who underwent an ethics investigation due to financial misconduct related to an extramarital affair he was having with the wife of a former top aide.

But a case perhaps more similar to Moore's predicament was that of Bob Packwood, a Republican senator from Oregon, who in the early 1990s was charged by an ethics investigation with a series of sexual harassment and official misconduct charges.

The committee investigating Packwood said he had engaged in a "pattern of abuse of his position of power and authority."

Both Ensign and Packwood ultimately resigned before the votes to expel them went before the Senate.