Democratic voters, too, appear not to be focused with singular intensity on impeachment: Ms. Warren’s rhetoric on the matter drew loud applause, but no louder than the crowd’s reaction to her arguments about climate change, racial inequality and government corruption.

Among the people in Ms. Warren’s audience, there was a sense of outrage about Mr. Trump’s conduct and a sense of support for the steps taken this week by House Democrats to investigate him more aggressively.

But there was little optimism that Mr. Trump might ultimately be removed from office, and some expressed anxiety at the unpredictability of the impeachment process.

Tim Butterworth, a retired teacher who is supporting Ms. Warren, said he believed the House had a duty to proceed with impeachment even though there was “kind of a stone wall” waiting in the Republican-controlled Senate. Mr. Butterworth did not mention Ms. Warren’s support for impeachment among his reasons for supporting her, focusing instead on her plans for addressing economic inequality.

“I think it would be easier to defeat him in an election,” Mr. Butterworth, 75, said of the president. “But when you see a crime being committed, you have to report it. If you don’t, you’re complicit.”

Ellen Moran, an undecided voter who works in urgent care, expressed both exasperation with Mr. Trump and some trepidation about impeachment. Ms. Moran, who is deciding between Ms. Warren and Pete Buttigieg, the mayor of South Bend, Ind., said it was “embarrassing, frankly, as an American that we have to come down to this.”