DETROIT — Speaking at one of Joe Biden’s biggest events so far, Sen. Kamala D. Harris (D-Calif.) and Sen. Cory Booker (D-N.J.) told Michigan voters that Democrats need to rally around the former vice president if they want to defeat President Trump in November.

Harris endorsed Biden on Sunday morning. Booker endorsed him 24 hours later, and then made his first campaign appearance with the former vice president in Flint earlier Monday.

“There is one man now who’s ready to go to the center of the arena, who is our best shot to beat Donald Trump,” Booker told a roaring crowd of 2,000 in Detroit.

Biden, he said, “is the best one to bring dignity back to that office. He is the best one to stand up for all of us in America … We can’t pray that he wins. We can’t hope that he wins. We can’t wish that he wins. We’ve got to vote him in.”

A few moments later, in her first public comments at a Biden campaign event, Harris said she believes that “there is a conscious attempt to try and disillusion us, to try and have us believe that the system will never work for us.”

She told the crowd she got to know Biden through his late son Beau, who was attorney general of Delaware when she held the same office in California. Later, she contrasted Biden with Trump.

“Donald Trump, he does not see people. The only people who he sees [is the person] he sees when he looks in the mirror,” she said. “We need a president who sees us, who understands us.”

The event was briefly interrupted by protesters against the U.S.-Mexico-Canada trade agreement and later by people calling for more green jobs.

The senators’ dual endorsements mirrored the rapid-fire endorsements a week ago, when Sen. Amy Klobuchar (D-Minn.) former South Bend Ind., mayor Pete Buttigieg and former Texas congressman Beto O’Rourke endorsed Biden in the hours before the Super Tuesday primaries.

Since then, Biden has had a delegate lead over Sen. Bernie Sanders (I-Vt.) in what has become a two-man race.

In Detroit, Biden said how grateful he was that his former opponents had endorsed him — and how bittersweet it must be for them to be in this position.