“The Fake News Media is doing everything they can to crash the economy because they think that will be bad for me and my re-election,” Mr. Trump tweeted last week. “The problem they have is that the economy is way too strong and we will soon be winning big on Trade, and everyone knows that, including China!”

Mr. Trump has repeated the claims in private discussions with aides and allies, insisting that his critics are trying to take away what he sees as his calling card for re-election. Mr. Trump has been agitated in discussions of the economy, and by the news media’s reporting of warnings of a possible recession. He has said forces that do not want him to win have been overstating the damage his trade war has caused, according to people who have spoken with him. And several aides agree with him that the news media is overplaying the economic fears, adding to his feeling of being justified, people close to the president said.

The claims provide a ready target to help Mr. Trump deflect blame if the economy does tip into recession. But whether they could truly insulate the president on what could be a significant issue of the 2020 election after he has so conspicuously wrapped himself in the good economic news of the past two years remains an open question, and he and his advisers have sought to tamp down concerns that a downturn is on the way.