The president scheduled an announcement, and the scene in the Rose Garden was surreal. Cabinet officers and White House aides lined up and applauded when the president emerged from the Oval Office as if he were declaring victory in his confrontation with Democrats in Congress. And the president sounded as if he was doing just that, opening his remarks by saying that he was “very proud to announce today that we have reached a deal to end the shutdown.”

Only there was no deal, just a retreat. The president who said he would never reopen the government unless he secured money for his border wall agreed to reopen the government without money for his border wall.

Supporters of a wall were hardly fooled, excoriating Mr. Trump for giving in. “Good news for George Herbert Walker Bush: As of today, he is no longer the biggest wimp ever to serve as President of the United States,” Ann Coulter, the conservative commentator who prodded Mr. Trump to take a firmer stand in December, wrote on Twitter.

Breitbart News, the conservative news site once run by Stephen K. Bannon, the president’s former senior adviser, made clear the disappointment among Mr. Trump’s base with its banner headline: “Government Open ... And Border. No Wall.” So did The Daily Caller, another leading voice on the right: “TRUMP CAVES.” And The Washington Examiner agreed: “Trump blinks.”

Democrats were not exactly gracious in victory, barely containing their delight. “Hopefully, it means a lesson has been learned: Shutting down government over a policy difference is self-defeating,” tut-tutted Mr. Schumer. “It accomplishes nothing but pain and suffering for the country and the American people.”

By late in the day, a defensive Mr. Trump was insisting it was not a defeat. “I wish people would read or listen to my words on the Border Wall,” he tweeted. “This was in no way a concession. It was taking care of millions of people who were getting badly hurt by the Shutdown with the understanding that in 21 days, if no deal is done, it’s off to the races!”

Until now, of course, he had expressed little if any concern for those hurt by the shutdown, insisting instead that many of the 800,000 who went without pay for five weeks were on his side and wanted him to stand strong. Whether this episode prompts Mr. Trump to change his approach to governing, it has altered the politics of shutdowns leaving federal workers caught in the middle.