The heated Senate race in battleground Pennsylvania has tightened even further between Sen. Bob Casey (D-PA) and Republican challenger David McCormick as voters already start to cast their ballots. The neck-and-neck contest is one of several that could be the Senate majority-maker by determining whether Democrats hold on to the chamber with a razor-thin margin.

The Cook Political Report shifted the Pennsylvania Senate race between Democratic Senator Bob Casey and Republican Dave McCormick toward Republicans on Monday, just over two weeks before Election Day.

Democrats have a very, very thin path to keeping control of the Senate, where they currently have a 51-49 majority. West Virginia is considered gone following the retirement of Sen. Joe Manchin, and M