Sen. Bernie Sanders will get a pre-debate boost from Rep. Keith Ellison, the co-chairman of the Congressional Progressive Caucus, who will become the second member of Congress to endorse Sanders’ insurgent presidential campaign Monday, he told MSNBC.

Close video Sanders talks Clinton policy positions Presidential candidate Sen. Bernie Sanders talks about his opposition to the TPP, which he’s “been against since day one.” Sanders also talks about facing off against Hillary Clinton in the first Democratic debate saying there is plenty for them to… Presidential candidate Sen. Bernie Sanders talks about his opposition to the TPP, which he’s “been against since day one.” Sanders also talks about facing off against Hillary Clinton in the first Democratic debate saying there is plenty for them to… share tweet email Embed

“I’m endorsing Bernie because he is talking about the issues that are important to American families,” Ellison told MSNBC in an email via his spokesperson. “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 joins his fellow Progressive Caucus co-chairman, Rep. Raul Grijalva, who endorsed Sanders last week at a rally in Tucson, where Grijalva’s congressional district is based. Sanders will face off against his rivals Tuesday at the first Democratic debate in Las Vegas.

Sanders helped found the Progressive Caucus as a member of the House in 1991 and is currently the only member of the caucus from the Senate. The group, which started with six members, has grown into the largest caucus in the Democratic conference with 76 members.

Ellison, Sanders and Grijalva work closely together in Congress and often end up introducing bills together, including recent legislation to raise the minimum wage and ban private prisons.

“Bernie and I have stood together on progressive values for years,” Ellison added. “Bernie was a founder of the Congressional Progressive Caucus, and as one of the current co-chairs, we have a shared desire to help Americans who are struggling to get by.”

RELATED: Sanders: I’m more consistent than Hillary

While Sanders has surged in polls of Democratic voters, and is beating front-runner Hillary Clinton in the first-in-the-nation primary state of New Hampshire, the longtime independent has struggled to win support from Democratic elected officials. The lack of endorsers means Sanders’ campaign has few high-profile surrogates, though Ellison said he would do some speaking on behalf of the campaign.

Ellison said he was not concerned by the lack of endorsements. “I don’t think it’s a problem. What matters is that he is connecting to the American people and talking about issues that matter to them the most,” he said.

Where future Sanders congressional endorsements come from is less clear, congressional aides say. At least 26 members of the Progressive Caucus were already supporting Clinton as of July, according to a tally kept by the Hill newspaper.

Clinton met privately with the Caucus during a whirlwind visit to Capitol Hill that month, and Ellison and others emerged impressed.