“Every day, we see more, so why would we stop with a less-strong case?” Ms. Pelosi said. “If you’re going to go down this path, you have to make sure that the public has an understanding of why, and that when the president — if the president is impeached, that the Senate understands that they either honor the oath of office to protect and defend the Constitution of the United States, and if they don’t, the public will hold them accountable for not holding the president accountable.”

Ms. Pelosi said some Democrats had privately told her that they supported censuring Mr. Trump, which would involve a vote on the House floor to reprimand him, but she believes the move would have little effect.

“That’s a day at the beach for the president, or at his golf club, or wherever he goes,” she said.

More than 60 of the 235 House Democrats publicly support impeaching Mr. Trump, including more than half of those sitting on the Judiciary Committee, which has jurisdiction to initiate the proceedings. Most of them are from Democratic districts where voters are overwhelmingly favor such a move, but in the past few days two lawmakers who hold seats that are considered competitive — albeit in Democratic-leaning districts — have come out in support of opening an inquiry.

If the trend continues, Ms. Pelosi’s effort to hold off the drive toward impeachment could become more complicated, although people close to her maintain that she would feel no compulsion to change her stance unless it became clear that a House majority supported the step. On Wednesday, she reiterated that she felt “no pressure” from her colleagues to do so, nor was she pressuring them to hold back. But she also seemed to concede that tamping down on impeachment fervor within her ranks had grown more difficult in large part because of Mr. Trump’s conduct.

“Every day the president puts more grounds forward that says he is obstructing justice, and that has affected members,” Ms. Pelosi said. “It’s self-evident that he is obstructing justice. He’s ignoring subpoenas.”