A senior State Department official under President George W. Bush slammed the Trump transition team as "angry" and "arrogant" on Tuesday, and urged others to "stay away" from serving in the president-elect's administration.

"After exchange [with] Trump transition team, changed my recommendation: stay away," Eliot Cohen, a prominent national security expert who vehemently opposed Trump's candidacy, wrote on Twitter.

"They're angry, arrogant, screaming 'you LOST!' Will be ugly," he added.

Cohen, a well-known neoconservative who teaches at the John Hopkins School of Advanced International Studies, played a major role in encouraging right-leaning defense experts and foreign policy insiders to publicly denounce Trump during the election.

"We are unable to support a party ticket with Mr. Trump at its head," several Republican foreign policy professionals wrote in a letter spearheaded by Cohen in March. Cohen separately noted in an interview with Politico that Hillary Clinton was "the lesser evil by a large margin" in her race against Trump.

However, in a column published two days after Trump's stunning election victory, Cohen urged those who serve in military, diplomatic or intelligence posts to "continue to do their jobs" under the forthcoming administration because "having professionals serve who remember that their oath is to support and defend the Constitution ... will be more important than ever."

"You asked what I thought about going to work in a Trump Administration ...," he continued.

"It seems to me that if they are sure that they would say yes out of a sense of duty rather than mere careerism; if they are realistic in understanding that in this enterprise they will be the horse, not the jockey; if they accept that they will enter an administration likely to be torn by infighting and bureaucratic skullduggery, they should say yes."

Details about the specific exchange Cohen referred to on Tuesday remain unclear. A spokesperson for the Trump transition team did not return the Washington Examiner's request for comment.