Some Republicans are cheering on Sen. Bernie Sanders’ (I-VT) rise in the Democratic presidential primary, confident that Sanders as the Democratic nominee would not only lose to President Donald Trump, but also torpedo Democrats’ campaigns down the ballot.

However, Senate Majority Mitch McConnell (R-KY) isn’t too sure about that.

When a reporter asked McConnell on Tuesday if he believed, as several other Republicans do, that the democratic socialist’s victory in the primary would help maintain a GOP majority in the Senate, the Republican leader cautioned against underestimating Sanders.

“I’m reminded of when the Democrats back in 1980 were all pulling for Ronald Reagan to be the nominee because they thought he’d be the easiest to beat,” McConnell said. “I think Republicans speculating about which Democratic candidate for president would be the easiest to beat may be a bit foolish.”

“I think it’s going to be a contested general election with a lot of energy on both sides,” he continued. “And for myself I’ll leave it up to the Democrats to pick who they’d like to be their candidate.”

The GOP leader added that the Democratic candidates were all the same to him anyway, calling them “very, very far to the left.”

“It looks like moderate Democrats are an endangered species or may have disappeared already,” he said.

The Sanders campaign did not respond to request for comment at the time of publication.

Watch McConnell below: