With no decisive winner called in the tight race for Pennsylvania’s U.S. Senate seat, David McCormick’s campaign manager said Wednesday he believes the Republican businessman will topple Bob Casey, the incumbent Democrat.

Incumbent U.S. Sen. Bob Casey is not ready to give up his seat just yet, even as the margin of votes show the three-term senator trailing behind newcomer GOP candidate David McCormick in his re-election bid.

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.