Sen. Cory Booker (D-NJ) on Monday endorsed former Vice President Joe Biden for president, contradicting his earlier criticism of the Democrat frontrunner’s record on racial issues.

“The answer to hatred & division is to reignite our spirit of common purpose,” Booker, who dropped out of the Democrat presidential primary in January, said on social media. “He’ll restore honor to the Oval Office and tackle our most pressing challenges.”

“That’s why I’m proud to endorse Joe,” he concluded.

The answer to hatred & division is to reignite our spirit of common purpose.@JoeBiden won’t only win – he’ll

show there's more that unites us than divides us. He’ll restore honor to the Oval Office and tackle our most pressing challenges. That’s why I’m proud to endorse Joe. pic.twitter.com/RcsnZs5mfQ — Cory Booker (@CoryBooker) March 9, 2020

Booker was one of Biden’s staunchest critics while on the campaign trail, repeatedly calling out the former vice president’s past work with segregationist senators and his position on criminal justice reform.

The New Jersey Democrat said of Biden touting his previous work with Sens. James Eastland and Herman Talmadge: “He is a presidential nominee and to say something – and again it’s not about working across the aisle, if anything I’ve made that a hallmark of my time in the Senate to get big things done and legislation passed.”

“This is about him evoking a terrible power dynamic that he showed a lack of understanding or insensitivity to by invoking this idea that he was called ‘son’ by white segregationists who, yes, they see him, in him, their son,” he added.

Booker joins several former Democrat White House candidates that have endorsed Biden ahead of Tuesday’s crucial primary contests in Michigan, Idaho, Mississippi, Missouri, North Dakota, and Washington. Former South Bend, Indiana, Mayor Pete Buttigieg, Sen. Amy Klobuchar (D-MN), and former Rep. Robert Francis “Beto” O’Rourke (D-TX) threw their support behind the former vice president ahead of his strong performance on Super Tuesday.

On Super Tuesday, Biden won Maine, Texas, North Carolina, Massachusetts, Alabama, Arkansas, Minnesota, Oklahoma, Tennessee, and Virginia. Sanders took home California, Colorado, Utah, and his home state of Vermont.

A newly-released CNN poll shows Biden leading Sanders by double digits — 52 percent to 36 percent among Democrat voters — for the nomination.