WASHINGTON — Sen. Ben Sasse, R-Neb., who frequently clashed with former President Donald Trump but won a second term in 2020, is expected to resign before the end of the year, a source familiar with the move confirmed Thursday.As Trump ran for re-election in 2020, Sasse unloaded on him, saying Trump "kisses dictators' butts," "flirted with white supremacists," disparages women, “mocks evangelicals behind closed doors" and "treats the presidency like a business opportunity."“Ben brings intellectual curiosity, a belief in the power and potential of American universities, and an unmatched track record of leadership spanning higher education, government and the private sector.”The announcement kicks off a process, spelled out in Florida state law, that includes meetings between Sasse and officials in Gainesville, where the university is based.“We anticipate that will be accepted by the end of the year, and then he would resign before the end of the year and the Nebraska governor would select the replacement,” the source said.Sasse, 50, the former president of Midland University in Fremont, Nebraska, who served in President George W. Bush’s administration, was elected to the Senate in 2014."