Sanders, 78, who until recently was the front-runner in the party’s race to face Republican President Donald Trump in November, is now trailing in delegates and desperate to regain momentum after Biden, 77, received a rush of endorsements from party establishment figures following his strong “Super Tuesday” showing this week.

Below is a summary of Saturday’s events.

Biden called for Democratic unity against Trump at a rally in St. Louis, Missouri, shortly after Sanders attacked his record and Biden had warned against a primary “bloodbath.”

“We’re going to unite this party and unite this country,” Biden said.

Biden thanked former Democratic White House rivals who recently dropped out of the race and endorsed him, including Pete Buttigieg, the former South Bend, Indiana, mayor, and U.S. Senator Amy Klobuchar of Minnesota.

Biden also unexpectedly thanked supporters of Kamala Harris, fueling speculation that the former Democratic presidential candidate may be about to endorse him. Harris, a U.S. senator from California, has been weighing such an endorsement, according to a person familiar with her thinking.

Sanders attacked Biden at a Michigan rally on Saturday, hours after Biden’s warning against a “bloodbath” in the primaries involving the U.S. senator from Vermont and self-described democratic socialist.

Speaking to a crowd in the Michigan suburb of Dearborn, Sanders lambasted the former vice president for voting in support of the Iraq war and for trade deals he says cost millions of American jobs, including in Michigan and the Midwest.