The debate underscores partisan divisions in the country about whether to impeach the president.
For only the third time in modern history, lawmakers on the House Judiciary Committee are formally considering articles of impeachment against a sitting president in a debate that underscores the deep divisionsin the country.
The process began on Wednesday night, with lawmakers delivering impassioned statements for or against impeaching the president.
On Thursday, Democrats are putting the last touches on articles accusing Mr. Trump of abuse of power and obstruction of Congress, finalizing charges stemming from their two-and-a-half-month inquiry into what they say was a scheme by the president to pressure Ukraine to announce investigations of his political rivals.
For Republicans, Thursday’s meeting — called a “markup” because it gives members the opportunity to offer amendments and edits to the articles — is their last chance to try to derail the impeachment before the articles are expected to come to the House floor early next week.
That is unlikely to happen in the committee, which is firmly under the control of Democrats and led by Representative Jerrold Nadler of New York. Both sides expect the committee to vote along party lines by Thursday afternoon to send the articles to the full House.
But the committee debate is certain to be intense as Democrats make their case that Mr. Trump “ignored and injured the interests of the nation” and Republicans angrily accuse the president’s adversaries of waging an unfair assault on the presidency based on insufficient evidence.
The markup is a test of party unity under Pelosi as she seeks to prevent defections by nervous moderates.
The Judiciary Committee’s debate on Thursday is an important test of the party discipline that Speaker Nancy Pelosi has sought to maintain since late September, when she announced that the House would begin an impeachment inquiry against Mr. Trump related to the Ukraine matter.
Only two House Democrats voted against formalizing Ms. Pelosi’s impeachment inquiry in a House vote about a month later. It was a demonstration of remarkable unity within the caucus about using one of the gravest remedies in the Constitution to hold the president accountable for his actions.
But some moderate Democrats whose conservative-leaning districts voted for Mr. Trump in 2016 have in the past expressed concerns about impeaching the president.
There is no indication that any of the Democrats on the Judiciary Committee intend to break with Ms. Pelosi by voting against sending the articles to the full House. While the markup process allows them to offer amendments, few if any are expected to do anything to substantively change the charges.
Republicans look to denounce the impeachment process before Trump and voters.
Republicans have no expectations that they can prevent the Judiciary Committee from sending articles of impeachment to the full House, but Thursday’s markup session is a high-profile opportunity to denounce the process and try to undermine the Democratic case against the president.
Any amendments that Republicans offer are all but certain to be rejected on party-line votes by the committee, which is heavily skewed in favor of Democrats. But that may not prevent them from offering some of them and causing delays by requesting roll-call votes.
The Republicans could offer amendments to water down the impeachment articles, eliminate one or both of the articles entirely or change the wording in ways that Democrats would not accept.
Such changes could be intended to show Mr. Trump — who has watched hours of the impeachment hearings — and Republican voters that they are fighting back against attempts by Ms. Pelosi and House Democrats to impeach the president next week.
But Republicans are already looking past the House vote to a trial in the Republican-led Senate. Mr. Trump has said he is expecting to receive a fair trial that could include a robust defense by his allies and ends with a complete acquittal.
Trump lawyers consider adding Alan Dershowitz, the high-profile lawyer, to the president’s legal team.
As impeachment marches forward, Mr. Trump’s lawyers are discussing hiring Alan Dershowitz, a professor emeritus at Harvard Law School and high-profile lawyer who has frequently defended the president on television, to help with his defense during a trial in the Senate, according to people familiar with the discussions.
Several advisers to the president support making Mr. Dershowitz part of the team of outside lawyers to advise the White House on constitutional issues, they said. But no formal offer has been made to Mr. Dershowitz. Mr. Dershowitz declined to comment.
Catch up on some important background on the impeachment inquiry.
Mr. Trump and his advisers repeatedly pressured President Volodymyr Zelensky of Ukraine to investigate people and issues of political concern to Mr. Trump, including former Vice President Joseph R. Biden Jr. Here’s a timeline of events since January.
A C.I.A. officer who was once detailed to the White House filed a whistle-blower complaint on Mr. Trump’s interactions with Mr. Zelensky. Read the complaint.