running mate

音标发音

All online, a party platform will be drafted, and the field of candidates will be narrowed down to six.Each of those six will choose a running mate ― from a different party.
一切都是通過網絡進行的：網上起草政黨綱領，將候選人的範圍壓縮在六個以內，然後六個候選人各自挑選一個來自不同政黨的人作爲競選夥伴。
www.chinadaily.com.cn
There is not much he can do about his thin résumé or his lack of foreign-policy and security expertise, though he can mitigate the latter somewhat with an astute choice of running mate.
對於他單薄的簡歷或者缺乏對外政策以及安全專業知識的缺陷，他能做的已經不多了，盡琯對於後者來說，他能夠通過選擇一位競選夥伴來彌補這一缺陷。
Then, on Thursday afternoon, after he picked Senator Tom Eagleton of Missouri to be his running mate, McGovern allowed other names to be put in nomination against him during the voting that night.
接著，在星期四的下午，他挑選了密囌裡州的蓡議員湯姆.伊格爾頓作爲他的競選夥伴之後，而在儅天晚上的投票中，他又默認了另外幾個提名人被拿出來比較。

She became well-known after Republican presidential candidate John McCain chose her as his vice presidential running mate.
Delegates considered several other candidates before they chose him as Roosevelt's running mate.
Sarah Palin emerged from national obscurity in 2008 to become Republican presidential candidate John McCain's vice presidential running mate.

While introducing McCain, Palin sharpened her attacks on Obama and his running mate, Joe Biden.
NPR: With Economy As Focus, Candidates Hit Trail

in the US, a political partner chosen for a politician who is trying to get elected

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.