Grijalva, a Mexican-American liberal Democrat and co-chairman of the Congressional Progressive Caucus, will make the announcement when he appears on stage with Sanders at the rally, the Los Angeles Times reports.
“The positions he has taken and the values he holds are ones I share . . . I couldn’t sit on the sidelines and wait for the tea leaves to be read better,” Grijalva told the New York Times in an interview today.
Sanders, a Democratic socialist, was thought to have no chance at winning the election when he entered the race, but if public opinion polls and massive crowd turnouts are an indication — Sanders drew record-setting crowds of 11,000 when he spoke at the downtown Phoenix Convention Center earlier this summer — he's seeming less like a longshot candidate.
Grijalva's endorsement marks a major milestone in Sanders' campaign because his main rival, Democratic candidate Hillary Clinton, already has picked up about 100 congressional endorsements.
In the same interview with the New York Times, Grijalva also mentioned that as a Mexican-American, he hopes to help Sanders attract Latino and other minority voters: “Latino sectors of the country, African-Americans, people of color — they’re feeling the economic pain as much as anyone else.
"Bernie has good positions on immigration and education, which are fountain issues for the Latino community. There’s an opportunity to talk about those and expose the fact that Bernie is not just a one-tune candidate, which he’s not.”
Sanders' political rally begins at 7 p.m. in the Reid Park DeMeester Outdoor Performance Center in Tucson, an outdoor space that can hold about 7,000 people. (RSVP here.)
He is visiting a handful of western cities ahead of next week's first Democratic presidential debate in Las Vegas.