Jimmy Kimmel Live
Bernie Sanders.
On Thursday evening, comedian Jimmy Kimmel read Sanders a message from Trump that he apparently shared with Kimmel when he appeared on Kimmel's show the night before.
In the message, Trump said Sanders had "been treated very unfairly" and asked whether the Vermont senator would mount an independent bid for the presidency if he fails to win the nomination.
Sanders didn't take the bait.
"Well, I think there's a little bit of self service there," Sanders said. "You don't think he's really worried about me?"
He added, sarcastically: "I really do appreciate his concern for me. I know it comes straight from his heart."
Trump has repeatedly urged Sanders to mount a third-party bid, contending that Sanders hasn't been afforded a fair shot at the Democratic nomination.
Trump has admitted that Sanders' prolonged fight with Democratic presidential frontrunner Hillary Clinton benefits him.
"I don't want to hit Crazy Bernie Sanders too hard yet because I love watching what he is doing to Crooked Hillary. His time will come!" Trump tweeted earlier this year.
In a "Morning Joe" interview in April, Trump suggested that he'd borrow some of Sanders' attacks on Clinton, which he said have been effective.
"Bernie Sanders has a message that's interesting," Trump said. "I'm going to be taking a lot of the things that Bernie said and using them."
He added: "I can reread some of his speeches and I can get some very good material."