And later Monday, at a rally for Gov. Henry McMaster of South Carolina, Mr. Trump said, “They are the party of Maxine Waters.”

Ms. Sanders used the moment to put Mr. Trump forward as an exemplar of civility against the braying hordes of Democratic activists, whose “calls for harassment” are “unacceptable.”

“America is a great country, and our ability to find solutions despite the disagreements is what makes us unique,” she said. “That is exactly what President Trump has done for all Americans.”

But it was not just the White House that was tut-tutting the public shaming.

“I think civil disobedience has had an important role in the sweep of history, but when it is done well, it has always been done strategically and with the high ground,” said Senator Brian Schatz, Democrat of Hawaii, who has used his Twitter account to urge activists to stay focused on the policy issues that he thinks move voters. “We have to be careful not to pick every battle in every place, both literally and figuratively.”

Like much else in the Trump era, however, it is not clear whether the episodes of “disobedience” will continue or at least continue garnering attention when other controversies flare up.

And having just returned from a weekend campaigning with Senator Sherrod Brown of Ohio, Mr. Schatz said he felt reassured that, away from the raging fires of social media, most Democrats on the ballot “understand that they need to focus on economic issues and health care.”