Amy McGrath, a 2020 Democratic challenger for Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellOcasio-Cortez to voters: Tell McConnell 'he is playing with fire' with Ginsburg's seat McConnell locks down key GOP votes in Supreme Court fight Video shows NYC subway station renamed after Ruth Bader Ginsburg MORE's (R-Ky.) seat, on Friday endorsed former Vice President Joe Biden Joe BidenBiden leads Trump by 36 points nationally among Latinos: poll GOP set to release controversial Biden report Can Donald Trump maintain new momentum until this November? MORE's presidential bid.

“Honor and integrity are at the heart of everything Marines do. It’s why I believe so strongly that Joe Biden is the president who can return honor and integrity to the Oval Office," McGrath said in a statement released by Biden's campaign.

"Joe is the Democrat who can bring our country together, restore our reputation abroad, and bring real change to a nation torn apart by partisanship. We need that now more than ever," she continued.

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McGrath, a Marine veteran who came close to flipping a Republican-held House seat in 2018, officially filed to run for Senate late last year.

She raised nearly $11 million in the third quarter last year, but will likely face an uphill challenge in her bid to capture the seat, which the Cook Political Report rates as "likely Republican."

McGrath's endorsement comes days before the Democratic primary's first nominating contest in Iowa on Monday.

Kentucky's Democratic primary is set to take place on May 19.

A new NBC News-Wall Street Journal poll released on Friday showed Sen. Bernie Sanders Bernie SandersNYT editorial board remembers Ginsburg: She 'will forever have two legacies' Two GOP governors urge Republicans to hold off on Supreme Court nominee Sanders knocks McConnell: He's going against Ginsburg's 'dying wishes' MORE (I-Vt.) leading the crowded Democratic primary pack at 27 percent support, and Biden close behind at 26 percent.