Republican Senate candidate Dave McCormick stepped up his legal efforts to block the counting of undated mail ballots Friday, as incumbent Democrat Bob Casey came to the defense of four county election boards that defied the Pennsylvania Supreme Court and voted to include them in their final tallies.

Sen. Bob Casey is locked in a tight race with Dave McCormick in Pennsylvania. There will be an automatic recount of the votes, state officials say.

Republicans are going to court in Pennsylvania amid vote counting in the U.S. Senate election between Democratic Sen.