challenger

1. N-COUNT A challenger is someone who competes with you for a position or title that you already have, for example being a sports champion or a political leader. 挑戰者

The strongest challenger, Texas Democrat Martin Frost, has withdrawn from the race. 最強勁的挑戰者，德尅薩斯州的民主黨人馬丁·弗羅斯特已經退出了競選。