Sen. Bernie Sanders, I-Vt., will receive his first endorsement from Rep. Raul Grijalva, D-Ariz., during a rally in Tucson on Friday.

The Arizona Democrat is endorsing Sanders ahead of his first Democratic Debate with top rival Hillary Clinton in Las Vegas on Oct. 15 that will be aired on CNN.

Grijalva represents Arizona's 3rd Congressional District and is currently in his seventh term. He is a long time member of the Congressional Hispanic Caucus and co-chairman of the Congressional Progressive Caucus, which was co-founded by Sanders.

The Democratic presidential hopeful will make his first post-debate TV appearance on "The Ellen DeGeneres Show." The interviews after the debate allows voters to get a better sense of who the candidates really are.

DeGeneres previously had Clinton on her show calling her the "smartest and most qualified person for the job." Does Sanders stand a chance against the former secretary of state? She already has more than 100 endorsements since joining the 2016 presidential race compared to his one.

Yet, both candidates are considered front-runners for the Democratic nomination. Sanders has been catching up to Clinton in polls and in some states, surpassing her. Sanders has also drawn thousands of people to his campaign rallies and has already closed the fundraising gap between him and Clinton.

"You're looking at a candidate who has run in many, many elections, who has never run a negative political ad in my life and hopes never to have to run them," Sanders said when CNN asked about his debate tactics.

"And you're looking at a candidate who does not go about attacking people personally. I just don't do that," he added.

Sanders is leading Clinton in New Hampshire since August and is close to Clinton by single digits in Iowa.

The Vermont Senator talked to Latino Voters in a speech on Wednesday at the Congressional Hispanic Caucus Institute where he called Donald Trump's views on immigration "racist."