Crucial Senate showdown in key battleground state officially underway as Casey, McCormick win primaries

It's officially game on in Pennsylvania, as Republican candidate Dave McCormick and Democratic Sen. Bob Casey Jr. were projected the winners of the two major party Senate primaries in the northeastern battleground state.

Both candidates, who were unopposed in Tuesday's Democratic and GOP primaries, will now face off in a high-profile and expensive Senate showdown that is one of a handful across the country which will likely decide whether the GOP wins back the Senate majority.

McCormick...