PHILADELPHIA — Pennsylvania’s nationally watched U.S. Senate race between Democratic incumbent Bob Casey Jr. and Republican challenger Dave McCormick was still too close to call as of mid-morning on Wednesday,

Pennsylvania Sen. Bob Casey is vying for a fourth term against challenger and businessman Dave McCormick in an extremely close race that could ultimately play a role in the balance of power in the United States Senate.

One of Pennsylvania’s two U.S. Senate seats is before voters Tuesday. Incumbent Democrat Bob Casey is vying for a fourth term against republican challenger and businessman Dave McCormick. Let’s start with incumbent Senator Bob Casey.