With a wave of sexual misconduct allegations hitting Alabama GOP Senate candidate Roy Moore, Republicans in the upper chamber have largely withdrawn support for him and appear to be searching for a way to oust Moore if he is able to pull off a win in the December special election. Leadership is even threatening to expel him from the chamber by a two-thirds vote. A look at the paltry history of congressional expulsions suggests that Senate Majority Leader Mitch McConnell will have a real challenge if he is forced to go that route.
Only fifteen senators have been formally expelled from the Senate, and of those 14 were Civil War era members who were tossed for supporting the Confederacy. The only other expelled Senator was William Blunt from Tennessee way back in 1797 for treason. Since the Civil War, the Senate has held three separate votes on expelling members – for charges ranging from being a Mormon in 1909 to speaking in opposition to America's entry in WWI to conflict of interest. In each case, the Senate voted against expelling the member.
In lieu of expulsion, the Senate has managed to force members to resign when faced with serious ethical clouds or actual criminal convictions. McConnell himself was very active in the last two such efforts - Nevada Senator John Ensign (R) who resigned in 2011 following an investigation into conflict of interest charges during his cover-up of an affair, and Oregon Senator Bob Packwood (R), who resigned in 1995 before facing an expulsion vote for multiple sexual harassment charges.
The House of Representatives has a similar record with expulsions. Only two have been expelled for non-Civil War related reasons. In 2002, Representative James Traficant (D) in 2002 was kicked out following convictions of racketeering and bribery and Rep. Michael Myers (D), who was convicted in the Abscam sting.