Former US Vice President and Democratic presidential hopeful Joe Biden speaks at the SEIU Unions for All Summit in Los Angeles, California on October 4, 2019.Frederic J. Brown | AFP | Getty ImagesFormer Vice President Joe Biden called for President Donald Trump’s impeachment Wednesday in a speech marked by some of his sharpest criticism yet of the president.The 2020 Democratic presidential candidate joined many of his rivals in unequivocally saying Trump “should be impeached.” Biden had previously gone as far as backing the House’s inquiry into whether Trump abused his power by urging Ukraine to investigate the former vice president and his son Hunter.”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,” Biden said to applause during remarks in New Hampshire.”To preserve our Constitution, our democracy, our basic integrity, he should be impeached,” he added.Late last month, House Speaker Nancy Pelosi started impeachment proceedings into Trump. Democrats are looking at whether Trump overreached his power in an attempt to influence the 2020 election by requesting Ukraine probe Biden, one of his chief rivals for the presidency next year.Trump has lodged the unsubstantiated claim that Biden intervened to remove Ukraine’s chief prosecutor in order to stop an investigation into a Ukrainian energy company where the younger Biden was a board member. The president has also requested China probe the Bidens over unfounded accusations of wrongdoing related to Hunter Biden’s business interests there.In his remarks Wednesday, Biden said there is “no truth” to Trump’s charges against him and his son. “Zero,” he added.The president responded to the Democrat’s speech almost immediately in a tweet. Trump said it is “so pathetic” to see Biden “calling for my impeachment — and I did nothing wrong.””Joe’s Failing Campaign gave him no other choice!” the president wrote.Biden on Wednesday argued that Trump dredged up the allegations because he feared Biden as an opponent in 2020. Many early polls show Biden, one of the leading contenders for the Democratic nomination, beating Trump in key electoral states.The former vice president said Trump is “afraid of just how badly I will beat him next November.”Lawmakers have looked into efforts by the administration and Trump’s personal lawyer, Rudy Giuliani, to encourage Ukraine to investigate the Bidens. A whistleblower complaint that helped to spark the investigation also alleges the White House tried to cover up records of a July phone call between Trump and Ukrainian President Volodymyr Zelensky, during which Trump asked his counterpart to probe the Bidens.In a letter to House Speaker Nancy Pelosi on Tuesday, White House counsel Pat Cipollone said the administration would not cooperate with the impeachment inquiry. He called the proceedings “baseless, unconstitutional efforts to overturn the democratic process.”Responding to Trump’s tweet Wednesday, Biden in part told the president to “stop stonewalling the Congress.”Subscribe to CNBC on YouTube.