WASHINGTON — A bitterly divided House of Representatives voted Thursday to endorse the Democratic-led impeachment inquiry into President Trump, in a historic action that set up a critical new public phase of the investigation and underscored the political polarization that serves as its backdrop.
The vote was 232 to 196 to approve a resolution that sets out rules for an impeachment process for which there are few precedents, and which promises to consume the country a little more than a year before the 2020 elections. It was only the third time in modern history that the House had taken a vote on an impeachment inquiry into a sitting president.
Having resisted such a vote for months, Democrats muscled through their resolution over unanimous Republican opposition with only two of their members breaking ranks to vote no. The tally foreshadowed the battle to come as Democrats take their case against the president fully into public view, sending both parties into uncharted territory and reshaping the nation’s political landscape.
On the House floor, Speaker Nancy Pelosi presided over the vote in an unusually packed chamber, after a debate that was fraught with the weight of the moment. Ms. Pelosi read from the preamble of the Constitution, a picture of the American flag by her side, and declared somberly, “What is at stake in all of this is nothing less than our democracy.”
Representative Kevin McCarthy, Republican of California and the minority leader, quoted Alexander Hamilton, who warned in the Federalist papers against impeachment as a partisan tool. Lawmakers listened from their seats, stone-faced and somber, while members of the public watched from the crowded gallery above.
“We don’t know whether President Trump is going to be impeached but the allegations are as serious as it gets: endangering national security for political gain,” Representative Jim McGovern of Massachusetts, the chairman of the House Rules Committee, thundered from the House floor, adding, “History is testing us.”
Minutes after the vote, Stephanie Grisham, the White House press secretary, denounced what she said was “a sham impeachment” and “a blatantly partisan attempt to destroy the president.” In a statement, she added, “The president has done nothing wrong and the Democrats know it.”
Mr. Trump weighed in on Twitter: “The Greatest Witch Hunt In American History!”
The day was a stunning turn in a drama that has riveted Capitol Hill, and the nation, since Ms. Pelosi announced last month that House Democrats would begin an impeachment investigation into whether Mr. Trump abused his power to pressure Ukraine to smear his political rivals, declaring that he had betrayed his oath of office.
Practically speaking, the resolution adopted Thursday outlines the rights and procedures that will guide the inquiry, including the public presentation of evidence and how the president and his legal team will be able to eventually mount a defense.
But its significance was more profound: After five weeks of private fact-finding, Democrats signaled that, despite Republican opposition, they now had enough confidence in the severity of the underlying facts about Mr. Trump’s dealings with Ukraine, and enough public backing for pursuing their inquiry, to start making their case for impeachment before the American people.
Even as they voted, more revelations about the president’s pressure campaign trickled out, as Timothy Morrison, the top Russia expert on the National Security Council, testified privately four floors below in a secure room in the bowels of the Capitol. He confirmed that the United States ambassador to the European Union, Gordon D. Sondland, told a top Ukrainian official that security assistance would be withheld until the country committed to investigations, pointing to a quid pro quo at the heart of the impeachment inquiry.
The vote removed almost any doubt that Democrats would bring a full-fledged impeachment case against Mr. Trump. Less clear is how quickly Democrats can move to formalize their charges and whether, through public hearings and the presentation of new evidence, they can win over any Republicans.
Democrats have indicated that the next phase could move swiftly, if they are not derailed. With Thursday’s Halloween vote behind them, party leaders are aiming to conclude public fact-finding hearings in the Intelligence Committee by around Thanksgiving. The Judiciary Committee would then have several weeks to draft and debate articles of impeachment before a possible House vote on impeachment before Christmas.
If Mr. Trump is impeached, he will almost certainly be acquitted by a Republican-led Senate. And House Republicans are still strongly behind him. One by one, they came to the floor on Thursday to denounce an inquiry that they view as secretive and unfair, and to accuse Democrats of shredding important precedents in their zeal to oust a duly elected president.
“Trying to put a ribbon on a sham process doesn’t make it any less of a sham,” said Representative Jim Jordan, Republican of Ohio, while Representative Devin Nunes of California, the top Republican on the Intelligence Committee, said the panel had turned into “a cult.”
While Republicans have assailed the process, Mr. Trump’s defense of himself has been more blunt force, describing the inquiry as a “coup,” branding veteran officials who have cooperated “Never Trumpers,” and accusing Democrats of lying about what took place as he insists over and over again that his call with President Volodymyr Zelensky of Ukraine was “perfect.”
Democrats urged Republicans to view Thursday’s vote as a turning point, the moment when every House member must begin engaging with the evidence itself.
At least some Republicans seemed ready to do so, and were forming the core of their defense that Mr. Trump was only doing his job, and was justified both in pushing Ukraine to examine allegations of corruption and in withholding military assistance to ensure taxpayer dollars were wisely spent.
“Bring it on about substance, because our president was right — he was concerned about corruption,” Representative Lee Zeldin, Republican of New York, said at a crowded news conference after the vote.
Republicans worked feverishly to hold their ranks together in opposition to the measure, with Mr. Trump rallying support at the White House before the roll call. Though many of the rules are nearly identical to those Republicans adopted in 1998 when they impeached President Bill Clinton, party leaders insisted that supporting the resolution amounted to legitimizing what they view as an indefensible three-year campaign to undo the results of the 2016 election.
“Democrats are trying to impeach the president because they are scared they cannot defeat him at the ballot box,” Mr. McCarthy said. “Why do you not trust the people?”
Democrats cast the resolution in terms of duty and solemn obligation.
“The House impeachment inquiry is about abuse of power,” said Representative Hakeem Jeffries of New York, the chairman of the House Democratic Caucus. “It’s about betrayal. It’s about corruption. It’s about national security. It’s about undermining our elections. It’s about defending our democracy for the people.”
Once the voting began, the House chamber buzzed with activity. Ms. Pelosi could be seen on the floor counting the votes as they came in and tracking Democrats until the very last minute, leaving nothing to chance.
Representative Rashida Tlaib, the freshman Democrat from Michigan who gained notoriety on her first day in office for her expletive-laden cry to impeach the president, stared upward, watching the count on the electronic board recording members’ votes. When Ms. Pelosi read the final tally, Republicans erupted in shouts, trying to drown out Democrats as they proceeded with the rest of the scheduled votes.
Though it is not a perfect comparison to votes taken to authorize impeachment inquiries into Mr. Clinton and President Richard M. Nixon, Thursday’s outcome underscored the depth of partisan polarization gripping American politics. Democrats delivered a show of unity that just weeks ago seemed improbable, with even many moderate lawmakers who are facing difficult re-election races in conservative-leaning districts voting in favor of moving forward.
The two Democrats who voted against the resolution — Collin C. Peterson of Minnesota and Jeff Van Drew of New Jersey — are both centrists in tight races. The House's lone independent, Representative Justin Amash of Michigan, a former Republican who left the party after openly criticizing the president, supported it.
“Everything has been so divisive and toxic,” Mr. Van Drew, who has long opposed impeachment, lamented after the vote. “We’re so focused on these issues we’re not going to have the focus on issues you all care about so much, like health care, like prescription drugs, like infrastructure, that we really need to focus on.”
The House is scheduled to recess for one week beginning Friday. Lawmakers leading the impeachment inquiry intend to use that time to begin to wrap up closed-door witness depositions with government officials. Their targets remain ambitious, if perhaps unattainable, including John R. Bolton, Mr. Trump’s former national security adviser.
A lawyer for Mr. Bolton appeared in federal court in Washington on Thursday to ask a judge to decide whether another client of his, the former deputy national security adviser, Charles Kupperman, must respond to a subpoena to testify before impeachment investigators or obey a White House directive to defy it. The judge scheduled arguments for December, and Mr. Kupperman’s lawyer said that if Mr. Bolton were to sue, he would raise identical issues.
In a similar case, a different judge sharply questioned an administration lawyer on Thursday about the president’s attempts to block a subpoena for congressional testimony from the former White House counsel, Donald F. McGahn II. The judge suggested that the administration’s arguments posed a threat to constitutional checks and balances.
The resolution adopted Thursday lays out rules for public hearings, directs the Intelligence Committee to produce a public report of its findings and authorizes it to share all evidence collected with the Judiciary Committee, where lawmakers from both parties will weigh the strength of the evidence and debate whether it amounts to high crimes and misdemeanors. It also gives Mr. Trump’s lawyers rights to intervene in those proceedings and present a defense.
But the inquiry remains a high-stakes gamble for Democrats just over a year from the 2020 balloting, as their presidential contenders — some of whom would act as jurors in a Senate trial should the House vote to impeach — are already deep into their campaigns to try to defeat Mr. Trump.
Public polls in recent weeks have suggested a narrow majority of the nation backs the inquiry and believes the president’s actions warrant scrutiny. But support for Mr. Trump being impeached and removed appears weaker, and there has been no sign that his narrow but durable base of supporters has been troubled by the accusations.
Catie Edmondson, Charlie Savage and Emily Cochrane contributed reporting.