running mate

1. N-COUNT In an election campaign, a candidate's running mate is the person that they have chosen to help them in the election. If the candidate wins, the running mate will become the second most important person after the winner. 竞选伙伴[美国英语]

...Clinton's selection of Al Gore as his running mate. …克林顿选择阿尔•戈尔作为他的竞选伙伴。