After five years as the leading booster of the “birther” movement, Donald Trump conceded during a circus-like event Friday that President Obama was born in the United States.

The GOP nominee had promised “a big announcement” about the birther issue, giving the impression that the long-debunked conspiracy theory would be topic No. 1 at the event he planned at Trump International, his new ­hotel in Washington, DC.

Instead, he sang the hotel’s praises and stood by for 20 minutes as decorated military vets lavished him with praise amid wall-to-wall cable-news coverage.

‘President Barack Obama was born in the United States, period.’ - Donald Trump

When they finished, the mogul stepped to the podium and spoke for about 30 seconds on the deeply divisive birther issue, seen by critics as an attempt to undermine the legitimacy of the nation’s first black president.

“President Barack Obama was born in the United States, period. Now we all want to get back to making America strong and great again,” Trump said, the first time he publicly admitted he was wrong, although he issued no apology.

He also launched a bizarre new attack on Hillary Clinton, claiming that it was she who had spread the theory that Obama was born in Kenya instead of ­Hawaii, his actual birthplace — and patting himself on the back for clearing matters up.

“Hillary Clinton and her campaign in 2008 started the birther controversy. I finished it. I finished it,” he said, before abruptly leaving the podium without taking questions from angry reporters.

Some stood on chairs shouting questions, while others were blocked from following the rapidly retreating candidate.

The Donald then tried to lead a small pool of photographers and television crews on a tour of his hotel. But when a print pool reporter and producer were barred, the frustrated networks pulled their cameras and erased their footage.

Critics slammed Trump for not apologizing, and for spending more time promoting his hotel than addressing the issue.

“I really don’t quite know what to make of that except for that we got played again by the Trump campaign, which is what they do,” said CNN’s John King, adding that Trump had tricked them into covering the endorsements.

Clinton quickly attacked Trump for not apologizing.

“What Trump should do: for once in his life, own up to his mistakes. Apologize to the president, and to the American people,” she tweeted.

“Trump has spent years peddling a racist conspiracy aimed at undermining the first African-American president. He can’t just take it back,” she added in ­another tweet.

Rep. Gregory Meeks (D-NY) called it “a sad day for all Americans, not just for African-Americans,” and said the event was a Trump con job.

Speaking in DC at a Black Women’s Agenda forum before Trump’s event, Clinton ­denounced birther claims as ­attempts to undermine Obama.

“For five years, he has led the birther movement to delegitimize our first black president. His campaign was founded on this outrageous lie,” she said.

Obama himself weighed in, sounding incredulous that the Trump campaign even raised the debunked theory.

“I’m shocked that a question like that has come up at a time when we have so many other things to do. Well, I’m not that shocked, actually. It’s fairly typical [for Trump],” the president said.

For years, Trump was the most prominent proponent of the movement, and regularly tweeted on the subject.

“In his own words, @Barack­Obama ‘was born in Kenya, and raised in Indonesia and Hawaii.’ This statement was made,” Trump claimed in a May 2012 tweet.

“An ‘extremely credible source’ has called my office and told me that @BarackObama’s birth certificate is a fraud,” he added in August 2012 after Obama had released his long-form Hawaiian birth certificate.

As late as Wednesday, Trump would not acknowledge that Obama was born in the United States, declining to address the subject in a Washington Post interview published late Thursday.

“I’ll answer that question at the right time,” Trump said. “I just don’t want to answer it yet.”

With Post Wires