If the Senate takes up the repeal of “Don’t Ask, Don’t Tell” in this lame duck session, there’s a chance that some senators in both parties will cross the aisle. Here’s the math:

To pass the defense authorization bill, of which repeal is a provision, Democrats need 60 votes to override the filibuster, or at least two crossovers from the GOP to add to their 58-seat majority. Right now, at least five Republican senators are believed to be seriously considering voting for repeal: Olympia Snowe and Susan Collins of Maine, John Ensign of Nevada, Lisa Murkowski of Alaska, and Richard Lugar of Indiana. If two or more of these senators commit to voting for the bill and repeal, the Democrats have their supermajority.