ROCHESTER, N.H. (CBS) – Speaking in New Hampshire on Wednesday, former Vice President Joe Biden called for President Donald Trump to be impeached. It’s the first time the candidate for the 2020 Democratic presidential nomination has called for impeachment.

“Donald Trump has violated his oath of office, betrayed this nation and committed impeachable acts,” Biden said at a campaign appearance in Rochester. “To preserve our constitution, our democracy, our basic integrity, he should be impeached.”

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Other candidates in the Democratic primary, including Massachusetts Sen. Elizabeth Warren have already called for Trump to be impeached. Now the former vice president is joining the effort, and on Wednesday he recounted how Trump told reporters that Ukraine and China should investigate the Bidens.

“He did it while standing in front of reporters and cameras like I am in this moment, in the broad light of day,” Biden said.

Biden asserted that “no president in American history has ever engaged in such unimaginable behavior.”

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“With his words and his actions, President Trump has indicted himself,” Biden said. “He’s already convicted himself in full view of the world and the American people.”

Biden’s campaign noted that the former vice president is not yet calling for Trump to be removed from office, but he does believe that the House of Representatives should impeach and the Senate should hold a trial.

In an interview with WBZ’s Liam Martin, Biden explained why he now supports impeachment.

“What’s changed is his conduct, it’s just over the top,” Biden said. “I mean there is no way to deny when the guy says ‘I’ve asked China, I’ve asked Russia, I’ve asked you know, to get engaged.’ You’re not allowed to do that. Presidents don’t do that.”

Trump responded to Biden’s remarks in a tweet.

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Biden’s call for impeachment comes as more polls show Warren polling ahead of him nationwide and in key early voting states.