Former Vice President Joe Biden endorsed “tenacious” Sen. Dianne Feinstein (D-CA) in her reelection bid for the United States Senate on Thursday and praised her for her “progressive values.”

“She’s tenacious. She’s accomplished. And she’s exactly who we need in the Senate to stand up to this Administration and its Republican allies in Congress,” Biden said in a statement, according to the Hill. “Dianne is a dear friend, and I’m proud to endorse her re-election.”

The 84-year-old Feinstein, who is seeking re-election to a sixth term in the Senate, reportedly said, “I”m so honored that Joe has endorsed my re-election — his support is a big deal.”

In a tweet, Feinstein said, “Thanks Joe – I’m proud we served together in the Senate and that you are on my side in this campaign!” referring to Biden’s decision to back her over her fellow Democratic rival state Senate President Pro Tem Kevin de León (D-Los Angeles).

Former VP @JoeBiden has endorsed my re-election! Thanks Joe – I’m proud we served together in the Senate and that you are on my side in this campaign! — Dianne Feinstein (@DianneFeinstein) March 29, 2018

Feinstein added: “I was honored to serve in the Senate with Joe Biden and to work with him to pass the Assault Weapons Ban and the Violence Against Women Act. Thank you, Joe, for endorsing my re-election campaign!”

I was honored to serve in the Senate with @JoeBiden and to work with him to pass the Assault Weapons Ban and the Violence Against Women Act. Thank you, Joe, for endorsing my re-election campaign! #Herstory — Dianne Feinstein (@DianneFeinstein) March 29, 2018

Although Feinstein is the clear favorite in one of the nation’s most closely-watched political races, the California Democratic Party declined to endorse her re-election at its annual convention in San Diego last month.

A poll released by the nonpartisan Public Policy Institute of California (PPIC) found that Feinstein is leading De León by a wide margin. Feinstein has 42 percent support among likely voters compared with 16 percent for De León.