As Joe Biden pulled off a series of surprising Super Tuesday upsets and the other remaining contenders for the Democratic presidential nomination faded, Sen. Bernie Sanders (I-Vt.) previewed how he plans to tangle with the vice president in what could quickly become a two-man race.

Speaking from his home state of Vermont, Sanders reminded supporters that despite his wins in earlier primaries and caucuses, he entered the race as an underdog candidate. To be one of the top two candidates by Super Tuesday, Sanders suggested, was worth celebrating.

By late Tuesday, Sanders had been declared the winner of primaries in Vermont, Colorado, Utah and California — the state with the greatest number of delegates. But Biden picked up wins in Alabama, Arkansas, North Carolina, Oklahoma, Tennessee, Virginia, and Texas ― as well as in Massachusetts and Minnesota, two stunners for him. The two candidates also were locked in a too-close-to-call race in Maine, where the neighboring Vermonter had been expected to do better.

Sanders, who had limited his campaign criticism of other Democrats up to now, unloaded on Biden in his Tuesday night speech without mentioning his name. Sanders reminded voters of some of Biden’s least progressive stances throughout his decades-long political career― and policies that remain deeply unpopular with core Democratic voters.

“One of us in this race led the opposition to the war in Iraq. You’re looking at him. Another candidate voted for the war in Iraq,” Sanders said.

“One of us has spent his entire life fighting against cuts in Social Security, and wanting to expand Social Security. Another candidate has been on the floor of the Senate calling for cuts to Social Security, Medicare, Medicaid and veteran’s programs,” he continued.

“One of us led the opposition to disastrous trade agreements which cost us millions of good-paying jobs. That’s me. And another candidate voted for disastrous trade agreements.

“One of us stood up for consumers and said we will not support a disastrous bankruptcy bill. And another candidate represented the credit card companies and voted for that disastrous bill,” the senator concluded.

Sanders entered Super Tuesday leading the delegate race. But after Biden’s blowout win in South Carolina’s Saturday primary and a surge of high-profile endorsement that followed, the former vice president was expected to perform well in the Southern states voting on Super Tuesday. But with the centrist vote largely consolidated after Sen. Amy Klobuchar of Minnesota and Indianan Pete Buttigieg exited the race and joined those supporting Biden, he pulled off bigger-than-expected victories.

Biden, speaking to supporters in Los Angeles Tuesday night, took note of the dramatic turnaround in his fortunes. “When you got to Super Tuesday, it’d be over” for him, he noted that some analysts had predicted. “So I’m here to report, we are very much alive.”

In a clear jab at Sanders, he said, “People are talking about a revolution, we started a movement. We’ve increased turnout.”