WASHINGTON — This city’s biggest party is turning into the must-miss event of the year.

The Trump administration said on Tuesday that the entire White House staff would skip next month’s White House Correspondents Dinner as a gesture of solidarity with President Trump, a severe critic of the news media who has already said that he will not attend.

Mr. Trump’s snub will signify the first time since the 1970s that a president has skipped the event, a celebrity-laden fixture of the Washington social calendar that is usually meant to symbolize comity between politicians and the press.

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But the absence of the entire White House staff — including the press secretary, Sean M. Spicer, along with cabinet secretaries and powerful advisers — may be unprecedented in the dinner’s history, and it comes with tensions between journalists and the administration at a fever pitch.

In a statement on Tuesday, Mr. Spicer said the decision was fueled by the administration’s displeasure with how Mr. Trump had been treated by the press.

“The staff is standing in solidarity with the president, who has been treated unfairly,” Mr. Spicer wrote. “We hope, including the president, that things improve and we can attend next year.”

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Major publications like Vanity Fair, The New Yorker and Bloomberg News have already canceled their usual parties held on the weekend of the dinner, which in recent years attracted boldface names from Hollywood and New York. Those moves were welcomed by some critics who chafe at the cozy atmosphere at the dinner, where reporters and the politicians they cover mingle and mock one another.

Supporters of the event say the evening is meant to celebrate the First Amendment, recognize quality political journalism and raise money for scholarships. Its sponsor, the White House Correspondents’ Association, said on Tuesday that it was disappointed that the administration staff would not attend.

“The W.H.C.A. board regrets this decision very much,” the association’s president, Jeff Mason, wrote in a letter to members. “We have worked hard to build a constructive relationship with the Trump White House and believe strongly that this goal is possible.”

Mr. Mason, a reporter for Reuters, said that Mr. Trump, Vice President Mike Pence and White House aides were still welcome to attend. “Only the White House can speak to the signal it wants to send with this decision,” Mr. Mason wrote.

Mr. Trump is an avid consumer of his news coverage, but his administration’s disdain for the establishment press runs deep. The president’s chief strategist, Stephen K. Bannon, once ran the right-wing news and opinion website Breitbart News, where he prohibited his staff members from attending the correspondents’ dinner. Other news organizations, including The New York Times, also do not allow their journalists to attend.

The master of ceremonies for the dinner is typically a celebrity entertainer or comedian, but no host has been announced yet for this year’s event.