Mitt Romney on Friday became the highest-profile Republican to vow not to vote for Donald TrumpDonald TrumpWashington Post reporter compares DC rioters to Boston Tea Party Women's march reaches Antarctica Steinem: If Trump creates Muslim registry, we'll all register MORE if the controversial businessman becomes the GOP presidential nominee.
“I’ll either vote for a conservative who runs or I’ll write in the name of a conservative," Romney said during an interview on the "Fox Business Network" on Friday.
"I’m going to vote for the nominee, but it’s not going to be Donald Trump," Rubio said on a radio program.
“I can’t even imagine that, and I don’t even want to imagine that right now, to be honest with you. I don’t believe it’s ever going to happen. It’s one of those bridges you hope you never have to cross," he added.