Pennsylvania’s U.S. Senate race between three-term Democratic Sen. Bob Casey and Republican challenger David McCormick will help determine control of the chamber Tuesday in a battleground state contest that is one of the nation’s most expensive this year.

McCormick sought to portray Casey as a do-nothing politician who had served 18 years in the Senate and had few legislative victories. Casey attacked McCormick for leading a wealthy hedge fund that sometimes invested in China and for giving a misleading picture of his record as CEO of a company in Pittsburgh.

Democratic Sen. Bob Casey and Republican challenger David McCormick face each other in Pennsylvania's high-stakes U.S. Senate contest.

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.

Democratic incumbent Sen. Bob Casey Jr. faces a well-financed challenge from Republican Dave McCormick in Pennsylvania’s nationally-watched U.S. Senate race. While Casey held a lead for much of the campaign,