Former Vice President Joseph R. Biden Jr. will call on Tuesday for impeachment proceedings against President Trump if the president does not comply with congressional requests for information related to Ukraine and other investigations.
In a speech scheduled for 2:30 p.m. in Wilmington, Del., Mr. Biden will “make the point that Trump’s latest abuses are on top of all of his prior abuses,” a campaign aide said. The aide said that Mr. Biden would call on the president to comply with “all of Congress’s outstanding, lawful requests for information — in the Ukraine matter and in other investigations — and if Trump does not comply, Congress has no choice but to impeach.”
Several other presidential candidates, including Senators Elizabeth Warren of Massachusetts and Kamala Harris of California, have already called for impeachment. Ms. Warren has been particularly forceful, accusing Congress of shirking its constitutional responsibilities.
“After the Mueller report, Congress had a duty to begin impeachment,” Ms. Warren tweeted on Friday. “By failing to act, Congress is complicit in Trump’s latest attempt to solicit foreign interference to aid him in US elections. Do your constitutional duty and impeach the president.”
During a news conference in Davenport, Iowa, on Tuesday, Senator Bernie Sanders of Vermont also called on the Judiciary Committee to begin an impeachment inquiry. But he stopped short of directly calling for Mr. Trump’s impeachment.
“What the Congress must do is keep its eyes focused on the needs of the working people of this country as it goes forward with the impeachment inquiry and the likely impeachment of Donald Trump,” he said. “Enough is enough, and today I hope very much that the Judiciary Committee will go forward with an impeachment inquiry.”
Mr. Biden has not unequivocally supported impeachment, though in the spring he said Congress would have “no alternative” to impeaching if it determined Mr. Trump was trying to impede investigations into Russian election interference.
In the House, the recent reports that Mr. Trump pressured Ukraine’s president to investigate Mr. Biden’s son Hunter and his financial dealings with a Ukrainian natural gas company have led many previously reluctant Democrats to support impeachment proceedings.
A series of moderate lawmakers, including freshmen from swing districts, have gotten on board this week, and Speaker Nancy Pelosi will meet Tuesday afternoon with committee leaders who have led investigations of the president.
Mr. Trump spoke to the president of Ukraine, Volodymyr Zelensky, shortly after he froze military aid to the country, which is battling Russian-controlled separatists. At the United Nations on Tuesday morning, Mr. Trump said he had held up the aid because other European countries had not paid enough to support Ukraine. He released the aid under pressure from Congress after the delay was publicly reported.
Mr. Biden’s campaign has said his son did nothing wrong in Ukraine. He has accused the president of abusing his power to extract a “political favor.”
The controversy erupted last week with reports that a whistle-blower had filed a complaint about Mr. Trump’s dealings with a foreign government.
Mr. Trump acknowledged on Sunday that he had discussed Mr. Biden in a July phone call with Mr. Zelensky. On Tuesday, he said on Twitter that he had authorized the release of the transcript of the call. His administration is refusing to provide the full whistle-blower complaint to Congress.
Katie Glueck and Sydney Ember contributed reporting.