In an email to reporters, Paul's team plastered a photograph of Trump under the headline "Donald Trump to Endorse Harry Reid," as it ridiculed the self-proclaimed Republican for his varied political history. "Please explain to us why anyone would care," the email said.

"Please explain why [Nevadan voters] should consider the opinion of a billionaire from New York who endorsed the arch enemy of all Republicans in Nevada, and really the enemy of all Republicans in the U.S."