But it was unclear what had provoked the president’s flurry of activity, and even advisers were searching for the normal cues that set him off: White House officials performing poorly on the Sunday show circuit, or the president’s delayed distillation of negative coverage from the week before.

Mr. Trump on Friday was rebuked by Senate Republicans, 12 of whom voted with Democrats against a national emergency to build a border wall. But the border barely figured into Mr. Trump’s weekend tweets, which appeared to be driven more by idle hands and an empty weekend schedule.

People who spoke with Mr. Trump on the phone over the weekend said he seemed to be in good spirits. Others who communicated with him said he had spent some time railing privately against Andrew G. McCabe, the former deputy F.B.I. director. But they also said he appeared to be a little aimless, and the outpouring seemed to be more driven by a lack of structure. Mr. Trump had skipped his regular weekend trip to Mar-a-Lago, his Florida estate, because of a family commitment that kept him grounded in Washington.

There was a four-hour lull in Mr. Trump’s online activity on Sunday, when he left the White House to visit St. John’s Church for St. Patrick’s Day. But for the most part, the president — bored, agitated or both — appeared to spend the weekend online.

Mr. Trump shared with his 59.1 million followers a report circulating on right-wing sites that Minnesota Democrats had grown unhappy with Ms. Omar, and accused a “Democrat” union leader in Ohio of standing in the way of putting an idling General Motors plant in the state back into operation.

Jack Posobiec, a Trump supporter known for advancing conspiracy theories on Twitter, including “Pizzagate,” marveled that his messages were being retweeted by the leader of the free world. The president shared two tweets initially sent by Mr. Posobiec, one a local news article about an MS-13 gang stabbing, and another criticizing CNN over a segment examining the links between Mr. Trump and white nationalism.

“I realize the president’s just reading my Twitter account going through the tweets,” Mr. Posobiec said in a 13-minute video he posted analyzing the experience. “Let’s see what else he’s up to today.”