Donald Trump has heaped gushing praise on Sydney Sweeney’s provocative new jeans advert after learning the Hollywood star was a registered Republican.

Only hours after learning about the actress’s reported political loyalties, the US president went on Truth Social on Monday, describing her American Eagle commercial the “‘HOTTEST’ ad out there.”

“Sydney Sweeney, a registered Republican, has the ‘HOTTEST’ ad out there,” he wrote.

“It’s for American Eagle, and the jeans are ‘flying off the shelves.'”

But Trump was less enthusiastic about another celebrity – pop superstar Taylor Swift – who he has previously labelled “woke”.

“Or just look at Woke singer Taylor Swift. Ever since I alerted the world as to what she was by saying on TRUTH that I can’t stand her (HATE!),” Trump wrote.

“She was booed out of the Super Bowl and became, NO LONGER HOT.”

Trump ended his tirade with “WOKE is for losers” and that the “Republican Party is what you want to be.”

He first heard of Sweeney’s political sympathies on Sunday when speaking with media at an airport in Pennsylvania.

A reporter asked him about the Sweeney advertising campaign for American Eagle, pointing out that she was a Republican.

“She’s a registered Republican?” Trump asked. “Now I love her ad.”

“Is that right? Is Sydney Sweeney…,” Trump continued.

“You’d be surprised how many people are Republicans. That’s one I wouldn’t have known, but I’m glad you told me that.”

“If Sydney Sweeney is a registered Republican, I think her ad is fantastic,” the president concluded.

The ad has been accused of pushing and promoting a discredited agenda often adopted by white supremacists in the US.

Following Trump’s remarks, American Eagle’s share price jumped 20 per cent when Wall Street closed on Monday (Tuesday AEST).