One month after President Trump was sworn in for a second term, Democratic despair and denial are giving way to an angry message from party activists and voters to their leaders.

Do something.

Across the country, anti-Trump protests and fiery town halls are flickering back to life. In polling, Democratic voters are venting disapproval at congressional Democrats. And in interviews this week with voters, activists and elected officials, many said Democrats were failing to curb Mr. Trump or offer a meaningful countermessage.

In an interview, Gov. Josh Shapiro of Pennsylvania, a Democrat, said that neither party was “effectively serving as a check on the executive branch,” and offered a striking rebuke of his side of the aisle.

“They are failing to address the real concerns that people have,” he said when asked on Thursday about congressional Democrats’ response to the early weeks of the new Trump administration.

Mr. Shapiro, who has filed a lawsuit over the Trump administration’s freeze of federal funding for Pennsylvania projects, added, “They’re failing to do what is their fundamental responsibility constitutionally — to be a check.”

The dawning reality of Republican control of the Capitol, punctuated by Mr. Trump’s eagerness to smash longstanding boundaries and enact retribution on his perceived enemies, has heightened Democrats’ sense of shock and outrage — and, increasingly, their frustration with their own leaders.