Ahead of the first Democratic debate on Tuesday, Vermont Sen. Bernie Sanders has scored another congressional endorsement.

Keith Ellison, the co-chairman of the Congressional Progressive Caucus, became the second member of Congress to endorse Sander’s surging presidential campaign on Monday, according to MSNBC.

“I’m endorsing Bernie because he is talking about the issues that are important to American families,” Ellison said in an email to MSNBC. “His candidacy is important for many reasons, but I believe the most important part of his candidacy is that it has the ability to create a renaissance in voter participation, which was at its lowest in decades this past election cycle.”

“We’ve all seen the massive crowds he is attracting, and I think that is a testament to his message connecting with people - people we will need to turn out in November,” Ellison added.

In endorsing Sanders, Ellison joins fellow Progressive Caucus co-chairman, Rep. Raul Grijalva, who endorsed Sanders last week at a rally in Tucson.

Sanders also scored an endorsement from the National Union of Healthcare Workers on Monday.

Although Sanders’ upstart grassroots campaign has gained momentum among Democratic voters and confounded pundits, he has struggled to win the support of Democratic elected officials, who have mostly flocked to Hillary Clinton thus far.

Regardless, Sanders will share the stage with Clinton on Tuesday, along with three other candidates: former Maryland Gov. Martin O’Malley, former Rhode Island Gov. Lincoln Chafee and former Virginia Sen. Jim Webb. The first Democratic primary debate begins at 8:30 p.m. EST, and will be broadcast live on CNN.