Sen. Bernie Sanders, Mayor Zohran Mamdani rally for left-of-center congressional candidates

Sen. Bernie Sanders and New York City Mayor Zohran Mamdani joined forces Thursday in a last-minute attempt to help three left-of-center congressional candidates win their primaries and defeat two sitting Democratic congressmembers.

Mamdani has a lot riding on the congressional primaries. His endorsements are regarded as a high-risk, but high-reward attempt to reshape Washington politics by sending left-leaning candidates to Congress.

"Now, people often ask me what I think of the state of the Democratic Party. This slate here today is our answer," Mamdani said. "The Democratic Party must change."

"Taking on [President] Trump is not enough," said Sanders, the most prominent icon of the democratic socialist movement.

The mayor is banking on his popularity with working class New Yorkers and his antipathy towards Israel to put his candidates over the top.

Mamdani has endorsed:  former comptroller Brad Lander, who is trying to defeat Rep. Dan Goldman; Darializa Avila Chevalier, who is trying to unseat Rep. Adriano Espaillat, and democratic socialist Claire Valdez, who wants to replace retiring Rep. Nydia Velazquez.

Velazquez endorsed Brooklyn Borough President Antonio Reynoso as her replacement.

The endorsements have upset moderate Democrats, especially Mamdani's decision to switch his allegiance from Espaillat to Chevalier.

Espaillat told CBS News New York political reporter Marcia Kramer he feels hurt.

"A race is not won by one endorsement," he said. "A race is won by the voters, and I've been out there speaking to the voters, listening to them, presenting my accomplishments and my future vision for the district."

Primary Day is Tuesday, June 23.