In a statement released by the Sanders campaign, de Blasio said he was supporting Sanders because he “stands with working families” and was the right candidate to take on President Donald Trump.

“I have called for a bold, progressive agenda, and that’s exactly what Sen. Sanders has championed for decades,” de Blasio said.

His choice is a reversal from four years ago, when he endorsed Hillary Clinton over Sanders, but it is not entirely unexpected. He said last summer that in retrospect, he believed Sanders would have won the 2016 election if nominated.

It is also notable that de Blasio chose to make the endorsement only now, after Sanders’ victory in New Hampshire and strong performance in Iowa have made him a clear front-runner for the nomination.

De Blasio was expected to travel with Sanders on Sunday and Monday in Nevada, where they will appear together at canvassing events ahead of the caucuses there on Feb. 22.

De Blasio and Sanders have spoken several times since the mayor ended his presidential campaign in September.

The mayor also spent time at Sanders’ vacation home in Vermont in 2018. Sanders swore de Blasio in at the inauguration for his second term as mayor.

Though de Blasio ran for mayor — and, later, president — on an unapologetically progressive platform, he has generally not endorsed progressive insurgents. He did not endorse Zephyr Teachout in 2014 or Cynthia Nixon in 2018 when they challenged Gov. Andrew Cuomo from the left. Nor did he endorse Tiffany Cabán in the Queens district attorney’s race last year, as Sanders and Sen. Elizabeth Warren of Massachusetts both did.

De Blasio’s backing adds to Sanders’ list of endorsements, which includes numerous unions and grassroots organizations as well as Reps. Alexandria Ocasio-Cortez of New York, Ilhan Omar of Minnesota and Rashida Tlaib of Michigan.

De Blasio was in the presidential race for only four months last year and never exceeded 1% in a debate-qualifying poll; even voters in New York did not support him. But his predecessor as mayor, Michael Bloomberg, has reached double digits in recent national polls with a veritable tsunami of spending from his personal fortune.

This article originally appeared in The New York Times .