ROCHESTER, N.H. — Joseph R. Biden Jr. on Wednesday called for President Trump’s impeachment for the first time, blistering Mr. Trump as a threat to American democracy and accusing him of “shooting holes in the Constitution.”
Escalating his language in an effort to rebut Mr. Trump’s unfounded claims about his actions with Ukraine, Mr. Biden set aside months of restraint to demand Congress move against the president.
“To preserve our Constitution, our democracy, our basic integrity, he should be impeached,” the former vice president told supporters here, accusing Mr. Trump of having “betrayed this nation.”
Mr. Biden linked Mr. Trump’s false claims to the so-called Big Lie idea promulgated by the Nazi propaganda minister Joseph Goebbels. “You say it long enough, often enough, people may believe it,” he said, invoking Goebbels by name.
While Mr. Biden stopped short of calling for Mr. Trump’s removal from office, his new aggressiveness marked an acknowledgment that he must do more to both confront a president who is attacking him daily and to halt his slide in the polls in the Democratic primary.
Mr. Trump is facing an impeachment inquiry in the House because of his request to the Ukrainian government that it look into what Mr. Biden did with the country when his son, Hunter Biden, was working for a gas company there. Mr. Biden again denied that he did anything improper as vice president. And he accused Mr. Trump, who has accused Mr. Biden of corruption and whose campaign is airing ads repeating the same claim, of acting entirely out of a desire to damage his candidacy.
“We’re not going to let Donald Trump pick the Democratic nominee for president, period,” said Mr. Biden, who has fallen behind Senator Elizabeth Warren of Massachusetts in a series of national and early nominating state polls. “He’s picked a fight with the wrong guy.”
The president apparently watched the speech, or was told of it, because even before it was over he noted on Twitter that Mr. Biden had called for his impeachment and claimed the Bidens had “ripped off at least two countries for millions of dollars.”
“Joe’s Failing Campaign gave him no other choice!” wrote Mr. Trump.
There is no evidence that Hunter Biden made millions of dollars from his overseas work or that his father intervened inappropriately with Ukraine or China, the other country Mr. Trump was alluding to in his tweet. The president has also urged China to look into the Bidens.
Mr. Biden again denied that he did anything improper as vice president. He noted that his 2016 call to fire Ukraine’s prosecutor general, Viktor Shokin, was United States government policy under President Barack Obama. It also reflected the wishes of a group of Republican senators at the time, who sought Mr. Shokin’s ouster because he was seen as unwilling to target corruption, Mr. Biden said.
A longtime senator before he became vice president, Mr. Biden is deferential to congressional prerogatives and has resisted calling for impeachment, even as Ms. Warren and many of his other Democratic rivals have been outspoken in demanding it. But as Mr. Trump and his allies wage political warfare against Mr. Biden, he has recently sought to mount a counteroffensive.
He began his rebuttal in a speech last week in Reno, Nev., but on Wednesday he went even further. Speaking from a teleprompter and dressed formally in suit and tie, he used his first trip back to New Hampshire since the impeachment investigation got underway to both taunt and condemn Mr. Trump in remarkably stark language.
“He’s afraid about just how badly I will beat him next November,” said Mr. Biden, attempting to frame the general election as a contest between him and the president, and appealing to Democratic voters here and elsewhere who are consumed with finding a nominee who can oust Mr. Trump.
But he also used his speech, which lasted just under 30 minutes, to warn of the damage he claimed Mr. Trump was doing to the country.
“We all laughed when he said could stand in the middle of Fifth Avenue and shoot someone and get away with it,” said Mr. Biden. “It’s no joke. He’s shooting holes in the Constitution, and we cannot let him get away with it.”