On Twitter, Mr. Trump has continued his usual drumbeat against the news media, but has cast a wider net by calling all “mainstream” journalists the enemy of the people.

“The Mainstream Media is under fire and being scorned all over the World as being corrupt and FAKE,” Mr. Trump wrote on Twitter on Tuesday. “For two years they pushed the Russian Collusion Delusion when they always knew there was No Collusion. They truly are the Enemy of the People and the Real Opposition Party!”

In a closed-door meeting with Senate Republicans at a policy lunch on Tuesday, where he promoted his emboldened administration’s decision to try to strike down the Affordable Care Act, Mr. Trump praised Mr. Barr for releasing such a quick summary of Mr. Mueller’s report.

“I love the A.G. He works fast. I love this guy. You told me I would,” Mr. Trump told the group, according to a person familiar with his remarks, before suggesting that he would not like to see any leaks coming from the meeting. He also shared his reasoning for doubling down on his targets.

“People love it when you attack the press,” he told the group.

The president’s targets include individual Democrats and law enforcement institutions. Senator Lindsey Graham, a White House ally, said he would investigate anti-Trump bias at the F.B.I. and Justice Department, presumably shifting the focus back to Mr. Trump’s Democratic opponent from 2016, Hillary Clinton.

Some of the targets have been happy to hit back.

Representative Adam B. Schiff, a California Democrat and vocal critic of the administration who heads the House Intelligence Committee, is among those facing pressure from the White House to resign. Asked by a reporter Monday evening whether he feared that Republicans would keep up the pummeling in a public hearing on Russia hosted by his committee on Thursday, Mr. Schiff laughed.