I'm still undecided (about) who to vote for.

我还拿不定主意投谁的票。

《牛津词典》

After college she was still undecided as to what career she wanted to pursue.

大学毕业后她仍无法决定自己要追求什么事业。

《柯林斯英汉双解大词典》

Mr Russell said he's still undecided whether to make an application with Guinness.

Russell先生说他还没有决定是不是要申请吉尼斯纪录。

youdao

A survey published by the research group ComRes on Tuesday said 2.5 million people who say they are certain to vote say they are still undecided who to vote for and more than a third of voters said it was "quite possible" they would change their mind on who to vote for by the time the polls open Thursday morning.

VOA: standard.2010.05.05

With only Florida's 29 electoral votes still undecided, Mr Obama won 303 electoral votes to Mr Romney's 206.

BBC: President Barack Obama defeats Romney to win re-election

With 9 percent of those polled still undecided, negative ads are flooding Missouri's airwaves.

CNN: Missouri heavyweights slug it out in heated Senate race

John Hoover said he's still undecided but that Obama did better than he expected.

NPR: Debate Didn't Change Minds Of Wavering Ind. Voters