Vice President Joe Biden Joe BidenOmar fires back at Trump over rally remarks: 'This is my country' Trump mocks Biden appearance, mask use ahead of first debate Trump attacks Omar for criticizing US: 'How did you do where you came from?' MORE said Sunday that President-elect Donald Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE ran “the most vicious campaign” he has ever seen.

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Speaking to Jake Tapper on CNN’s “State of the Union,” Biden estimated that only 10 percent of Americans could explain Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE’s plan to provide free education.

“It got drowned out by the most vicious campaign, the craziest campaign, I’ve ever witnessed,” Biden said.

Biden, who campaigned for Clinton and railed against Trump prior to the election, said much of the campaign was focused on keeping “the car from going off the cliff.”

“The bulk of the campaign was about emails or his boorish behavior,” Biden added.