"Maybe Donald negotiated a deal with his buddy @HillaryClinton. Continuing this path will put her in the White House," the former Florida governor tweeted.
Bush included a tweet sent from Trump's account moments earlier where the businessman touted polling figures
suggesting a majority of his supporters would stick with him should he drop out of the GOP race and run as an independent.
Republicans have battled with the possibility that the freewheeling real estate tycoon may become their party's nominee since he skyrocketed to the top of polls after entering the race over the summer, where he has remained. But they have worried about their chances should he run as an independent.
While Trump publicly patched things up with Republican Party officials when he signed a loyalty pledge in early September, his comments this week calling for a ban on Muslims entering the U.S. has prompted fierce criticism, including from GOP leaders.
GOP chairmen in the early-voting states of Iowa, New Hampshire and South Carolina have denounced Trump's latest remarks. Republican National Committee Chairman Reince Priebus earlier Tuesday also joined
a chorus of political voices disagreeing with his comments.
Bush has been lagging in polls for the GOP nomination for months, and his allied super-PAC this week released a new ad
aggressively going after Trump and other Republican rivals on the issue of national security and terrorism.