Trump called Sasse a "liability to the Republican Party and an embarrassment to the Great State of Nebraska" as well as the "least effective" Republican senator who "truly doesn’t have what it takes to be great" in a series of tweets Saturday morning. The president also suggested that the Republican party "should find a new and more viable candidate."
“Ben said the same thing to Nebraskans that he has repeatedly said to the president directly in the Oval Office. Ben is focused on defending the Republican Senate majority, and he's not going to waste a single minute on tweets," Sasse spokesman James Wegmann said in a statement Saturday morning.
The president also referred to Sasse as "Little Ben" and compared Sasse to former Sens. Jeff Flake and Bob Corker, both of whom criticized the president and decided not to run for reelection. The president suggested that Sasse, like Corker and Flake, could be the next "totally unelectable" legislator and retire from politics.
Sasse is up for reelection and is running against Democratic opponent Chris Janicek, who has faced criticism and calls to drop out after he sent sexually vulgar texts to a campaign staffer.
ABC News' Elizabeth Thomas and Ben Siegel contributed to this report.