President Trump on Thursday said it was "great" to see Republican Kelli Ward challenging Sen. Jeff Flake of Arizona, who the president labeled "toxic" and a "non-factor" in the U.S. Senate. "Great to see that Dr. Kelli Ward is running against Jeff Flake, who is WEAK on borders, crime and a non-factor in Senate. He's toxic!" Mr. Trump tweeted. The president's open embrace of a primary challenger to a sitting Republican senator comes as Mr. Trump prepares to head to Phoenix next week for a campaign rally, where he could formally endorse a challenger to Mr. Flake, who has emerged as a prominent Republican critic of Mr. Trump. Phoenix Mayor Greg Stanton on Wednesday urged Mr. Trump to postpone the rally, which is currently scheduled for Tuesday. Dr. Kelli Ward joined the Todd Starnes Show today to discuss President Trump's warm welcome and why she decided to run against Sen. Flake. Listen to the full interview below: