I'm the underdog,” David McCormick told NewsNation’s Leland Vittert in a one-on-one interview for “On Balance.”

With about one month before the election, incumbent Democratic Sen. Bob Casey faces GOP businessman Dave McCormick Thursday in their first debate.

Pennsylvania incumbent Sen. Bob Casey Jr. (D) and Republican challenger David McCormick will take the debate stage Thursday evening in Harrisonburg, Pa., as Democrats try to prevent