Sen. Bernie Sanders once called Donald Trump a “pathological liar,” but at a forum at George Washington University in Washington, DC, the self-described socialist praised the president-elect’s “extraordinary accomplishment” in winning the White House.

“Trump took on the Republican establishment, he took on the Democratic establishment, took on the media establishment and he ended up winning the election to become president of the United States. And that is an extraordinary accomplishment. And it talks about perseverance, it talks about very strong political instincts, it talks about a way to connect with people,” Sanders said.

“So I give Donald Trump his due,” he said.

It was just a month ago — after Trump secured the presidency in last year’s general election — that Sanders described the mogul-turned-politician in much worse terms.

“What do you do when you have a president-elect, soon to be president, who — and I say this not happily, but I think most people who observe him would agree — is a pathological liar who changes his mind every single day?” Sanders said Dec. 8 in an interview on MSNBC, saying Trump can’t be trusted to keep his word.