running mate
noun [ C ] uk/ˈrʌn.ɪŋ ˌmeɪt/ us/ˈrʌn.ɪŋ ˌmeɪt/
（美国政治选举中的）竞选伙伴
in the US, a political partner chosen for a politician who is trying to get elected
If a candidate for president wins the election, his/her running mate becomes the vice president. 如果总统候选人赢得选举，他／她的竞选伙伴就成为副总统。