Cranking up pressure on the US president, porn actress Stormy Daniels wants Donald Trump to answer her lawyer’s questions under oath about a pre-election payment aimed at keeping her quiet about their alleged tryst.

If she’s successful, it would be the first deposition of a sitting president since Bill Clinton in 1998 had to answer questions about his conduct with women.

Ms Daniels’ lawyer Michael Avenatti is seeking sworn testimony from Mr Trump and his personal lawyer, Michael Cohen, about a US$130,000 ($170,000) payment made to Ms Daniels days before the 2016 presidential election as part of a nondisclosure agreement she is seeking to invalidate.

Mr Trump has kept a low profile all week, as has first lady Melania Trump, who is spending the week in Florida.

White House spokeswoman Sarah Huckabee Sanders said Mr Trump had denied the allegations and directed further questions to outside counsel.

Despite the pushback, the persistent focus on Ms Daniels is a troubling distraction for a White House already struggling with an exodus of top staffers, a floundering agenda and the looming threat from the Russia investigation.

Ms Daniels, whose legal name is Stephanie Clifford, detailed her alleged 2006 tryst with Mr Trump in a widely watched interview with CBS’ 60 Minutes broadcast Sunday.

She said she’d had sex with him once, shortly after Melania Trump gave birth to the president’s youngest son.

Ms Daniels also said that a man approached her in a Las Vegas parking lot in 2011 when she was with her infant daughter, and threatened her with physical harm if she went public with her story.

The interview prompted a flurry of new legal action. 

-AAP