Cory Booker endorses Joe Biden for president. ‘He is the person to unify us.’

New Jersey Sen. Cory Booker has endorsed former Vice President Joe Biden for president, throwing his support behind his former Democratic presidential rival.

“@JoeBiden won’t only win — he’ll show there’s more that unites us than divides us,” Booker wrote on Twitter Monday morning.

Booker’s endorsement comes on the eve of another round of voting in which Biden is again counting on huge support from African American voters to continue his recent momentum against rival Sen. Bernie Sanders (I., Vt.). Michigan is the biggest of several states set to vote Tuesday, and black voters in Detroit and other cities there could play a decisive role.

Booker will campaign with Biden in Flint, Mich. and Detroit Monday ahead of the vote.

The senator isn’t the only former rival to back Biden in recent days. On Sunday, California Sen. Kamala Harris threw her support behind the former vice president, saying in a video he “speaks to the best of who we are and challenges us to live up to our ideals.” Minnesota Sen. Amy Klobuchar, former Texas Rep. Beto O’Rourke, and former South Bend, Ind., Mayor Pete Buttigieg have all endorsed Biden after ending their 2020 campaigns.

Booker and Harris will appear alongside Biden at a rally in Detroit Monday night. In the past, both have questioned Biden’s record on race. Booker had a viral moment during the August 2019 presidential debate when he snapped back at Biden for criticizing Booker’s criminal justice record while the mayor of Newark, N.J.

"You’re dipping into the Kool-Aid and you don’t even know the flavor,” Booker said, adding, "If you want to compare records, and frankly I’m surprised that you do, I’m happy to do that.”

Booker said Monday morning that he was convinced Biden has the understanding of racial issues to best unify the country, and noted that African American voters in the South and cities like Detroit “have played a pivotal role in my entire lifetime in choosing the Democratic nominee.”

“I know factually from talking to him that some of my biggest issues, like criminal justice reform, like racial justice, like economic justice, that he is going to be a strong leader on that and actually pull the country together with the kind of coalition we need to actually make progress in those areas,” Booker said on CBS.

He added that “of all the diversity in our party, of all the diversity across this nation, I think that at this particular time in history he is the person to unify us.”

Sanders, who narrowly won Michigan over Hillary Clinton in a huge upset in the 2016 Democratic primary, is hoping for a repeat performance that can stop Biden’s recent surge. He made several stops in the state over the weekend, including a rally Sunday night that drew more than 10,000 at the University of Michigan in Ann Arbor.

He touted endorsements from civil rights leader Jesse Jackson and support from U.S. Rep. Rashida Tlaib, of Detroit.

“I understand that Joe Biden has the support of the entire political establishment. I got that, but we have the support of some of the strongest grass roots movements in this country,” Sanders said Sunday night before a roaring, overwhelmingly young crowd. “We have the support of some of the best unions in this country, and I would 100 times over prefer to have grassroots support than establishment support.”

Said Booker, in his CBS interview: ""Bernie’s my friend. I have a lot of respect for him … I just want us to get beyond pointing fingers at each other, and trying to tear each other down. We can’t tolerate that right now. The threat [is] in the White House."

In addition to Michigan, five other states — Idaho, Mississippi, Missouri, North Dakota, and Washington — will cast their votes in the Democratic primary on Tuesday. Biden currently leads the race with 664 delegates, with Sanders close behind with 573. In all, 1,991 delegates are needed to win the nomination.

This is a developing story. Check back for updates. Tamari reported from Detroit.