Sen. Bob Menendez has shown no sign he will voluntarily resign from the Senate following his conviction on bribery charges. That leaves Democratic senators contemplating how to launch an expulsion effort to force him from office. While Menendez, a New Jersey Democrat, has six months remaining in his term, Democrats have made it clear they don’t want him in office any longer. Within minutes of the guilty verdict on Tuesday, Senate Majority Leader Chuck Schumer called for his resignation and New Jersey Gov. Phil Murphy, who would name Menendez’s replacement, said that the Senate should expel Menendez if he refused to step down. But expulsion, which requires a two-thirds majority to pass, is an exceedingly rare tool used by the Senate.