To give a casting vote投裁定票
N-COUNT（可数名词） When a committee has given an equal number of votes for and against a proposal, the chairperson can give a casting vote. This vote decides whether or not the proposal will be passed. (指赞成票和反对票持平时会议主席所投的) 决定票
The vote was tied and a union leader used his casting vote in favour of the return to work.
由于票数相同，一名工会领导投了决定票支持复工。