Donald Trump believes the Republican establishment is "warming up" to his candidacy as he ramped up his attacks against his chief rival, Ted Cruz.

Ted Cruz and Donald Trump speak to the moderators in the Fox Business Network Republican presidential debate in North Charleston, South Carolina. T (Photo by Scott Olson/Getty Images)

Trump claims he is getting many phone calls from establishment members of the GOP that want to join his team.

But declined to provide any names.

Trump painted himself as a pragmatic deal-maker capable of working with lawmakers, in contrast with Cruz.

Cruz is an ideological purist who has long argued that Republicans need to elect a conservative who will energize the base instead of another moderate.