The Pennsylvania Senate race between incumbent Bob Casey, left, and his Republican challenger, Dave McCormick, is headed for a recount. All counties must complete their recounts by Tuesday, Nov. 26. Pennsylvania's Senate race is going to a mandatory recount despite the Associated Press calling it last week for Republican challenger Dave McCormick.

A small margin in votes separating incumbent Democratic Sen. Bob Casey from Republican challenger David McCormick Jr. has triggered a recount in the Pennsylvania Senate race, the commonwealth's secretary said Wednesday.

The unofficial results in the race for the U.S. Senate seat in Pennsylvania have triggered a legally required statewide recount, Commonwealth Secretary Al Schmidt said on Wednesday. Democratic Senator Bob Casey and Republican Dave McCormick have vote totals within the one-half of 1 percent margin that triggers a mandatory recount under state law,