WASHINGTON — President Barack Obama exacted his revenge Saturday after weeks of attacks from his would-be Republican challenger Donald Trump, joking that the billionaire businessman could bring change to the White House, transforming it from a stately mansion into a tacky casino with a whirlpool in the garden.

With Trump in attendance, Pres. Obama used the White House Correspondents’ Association annual dinner to mock the reality TV star’s presidential ambitions. The president said Trump has shown the acumen of a future president, from firing Gary Busey on a recent episode of “Celebrity Apprentice” to focusing so much time on conspiracy theories about Pres. Obama’s birthplace.

Pres. Obama took time to rib some of those among the Republicans jostling to succeed him. He said he’d heard that Rep. Michele Bachmann of Minnesota was running for president, adding, “which is weird, because I hear she was born in Canada.”

He then singled out Trump.

After a week when Pres. Obama released his long-form Hawaii birth certificate, he said Trump could now focus on the serious issues, from whether the moon landing actually happened to “where are Biggie and Tupac?”

“No one is prouder to put this birth certificate matter to rest than ‘the Donald,'” Pres. Obama said, referring to Trump’s claims the same day that he was responsible for solving the issue.