Politico had an article today saying the GOP could elect to run multiple candidates this year on the Republican ticket. It was done by the Whigs in 1836. The idea is you prevent the other candidate from getting 270 electorals meaning there is no majority winner. The House of Rep - likely still in GOP hands - would then elect the President.
I hadn't heard this proposed before. It would likely blow up the party (and possibly the country) but I don't think Trump is doing them any good either.