Mr. Trump has continued to dismiss news stories as “fake news” when he considers them unflattering to himself or to his administration. In recent days he has focused his attention on The Washington Post, its owner, Jeff Bezos, and the company that made Mr. Bezos among the richest people in the world, Amazon.

On Friday, he turned his attention to stories suggesting that the Environmental Protection Agency administrator, Scott Pruitt, could replace his attorney general, Jeff Sessions, a seemingly implausible scenario given the ethical cloud hanging over Mr. Pruitt’s head.

But encouraging members of the executive branch to attend the April 28 dinner, even in his absence, in support of the First Amendment is a notable change.

Sarah Huckabee Sanders, the White House press secretary, will represent the Trump administration at the head table, where presidents and first ladies have sat in the past.

Last year’s boycott marked the first time a president had skipped the Washington tradition since Ronald Reagan in 1981, when Mr. Reagan was recovering from an assassination attempt.