Biden had previously refrained from making an outright plea for impeachment
US President Donald Trump added muscle to the legal team defending against an impeachment investigation led by congressional Democrats on Wednesday, after 2020 re-election rival Joe Biden called for the first time for his impeachment.
Biden, who is at the center of a controversy over Trump's dealings with Ukraine that led the Democratic-led US House of Representatives to open an impeachment inquiry, had previously refrained from making an outright plea for impeachment.
Trump continued to paint the probe as a partisan smear, and accused the US intelligence officer who filed the whistleblower complaint that sparked the furor of having political motives. He also added former US Representative Trey Gowdy, best known for his investigations of the administration of Trump's Democratic predecessor, to his outside legal team.
During a campaign stop in New Hampshire, Biden, the Democratic front-runner to face Trump in next year's presidential election, took the gloves off.
"With his words and his actions, President Trump has indicted himself. By obstructing justice, refusing to comply with a congressional inquiry, he's already convicted himself," Biden said. "In full view of the world and the American people, Donald Trump has violated his oath of office, betrayed this nation and committed impeachable acts."
"To preserve our Constitution, our democracy, our basic integrity, he should be impeached."
Trump fired back on Twitter.
"So pathetic to see Sleepy Joe Biden, who with his son, Hunter, and to the detriment of the American Taxpayer, has ripped off at least two countries for millions of dollars, calling for my impeachment - and I did nothing wrong," Trump wrote.
The House began impeachment proceedings against Trump last month over his attempts to have Ukraine's president investigate Biden and his son Hunter Biden, who was on the board of a Ukrainian gas company.
Despite Trump's allegations, which he made without evidence, that Biden engaged in improper dealings in Ukraine, there are few signs the controversy has damaged the Democratic former vice president's 2020 prospects.
Public opinion polls, including those taken by Reuters/Ipsos, have shown Biden's support remaining relatively stable.