Republican David McCormick is expected to announce his second bid for U.S. Senate in Pennsylvania, according to people familiar with his plans, taking on Democratic Sen. Bob Casey after narrowly losing an expensive and bruising GOP primary last year to a Donald Trump-endorsed rival. McCormick, 58, has strong support from the party establishment. With his deep pockets as a former hedge fund CEO, Republicans believe he will mount a strong challenge to the three-term Casey in a state that is critical to control of the White House and the Senate.