Ms. Pelosi’s announcement came as the House Judiciary Committee laid out the next steps for its formal impeachment proceedings against Mr. Trump. The committee said it would convene a hearing on Monday to allow its lawyers and those for the Intelligence Committee to formally present evidence in the inquiry.

The hearing may touch on one of the few remaining internal disputes among Democrats in an impeachment inquiry that has otherwise largely united them. Democrats must decide whether to limit their case to Mr. Trump’s dealings with Ukraine, or include earlier allegations that he obstructed justice in trying to thwart the special counsel’s Russia investigation.

On Thursday, returning to the ceremonial speaker’s hallway where she announced in September that Democrats were initiating the inquiry, Ms. Pelosi sent a clear signal that she was confident Democrats had the votes they needed to impeach Mr. Trump. But the proceedings, unfolding less than a year before the 2020 election, will play out amid profound partisan divisions and pose political risks for Democrats and Republicans alike, as much as for the president himself.

Democrats familiar with the matter believe the judiciary panel is on track to begin publicly debating and voting on articles by the end of next week, despite uniform Republican opposition. That would lay the groundwork for a possible vote to impeach the president by Dec. 20, the final day this year that Congress is scheduled to be in session.