Story highlights Warren blasted Trump for his comments about a federal judge due to his Mexican heritage

Vice President Joe Biden endorsed Hillary Clinton

Washington (CNN) Vice President Joe Biden endorsed Hillary Clinton Thursday night as he and Sen. Elizabeth Warren launched blistering back-to-back attacks at Donald Trump, both calling the presumptive Republican presidential nominee's comments about a federal judge "racist."

Biden was discussing the empty seat on the Supreme Court at the American Constitution Society for Law and Policy's 2016 National Convention in Washington when he weighed in on the 2016 race.

"Anybody who thinks that whoever the next president is -- and God willing, in my view, it will be Secretary Clinton," Biden said.

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A Biden source said there's "no question" this was an endorsement and expects the vice president to say more about Clinton in the coming days.

Clinton thanked Biden for his backing in a tweet Friday afternoon, referencing the vice president's infamous hot-mic moment in 2010 when he called the passage of Obamacare a "big f---ing deal."

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