The balance of the Senate could remain a mystery for several weeks after Nov. 8, thanks to an unusual election process in Louisiana that is likely to leave the political outcome of its Senate race unknown for another month.

With the Senate margin already expected to be razor-thin for either party, that could mean election night leaves the Senate hanging with 50 seats for one party and 49 for the other. Republicans today have 54 seats in the Senate, but are defending many more seats than Democrats, and are widely expected to lose a few and maybe even lose the majority.