President Donald Trump is upset with White House press secretary Sarah Sanders over her responses Wednesday regarding his alleged affair with porn star Stormy Daniels, a source close to the White House tells CNN.

Daniels, whose legal name is Stephanie Clifford, filed suit against Trump this week alleging he hadn't signed a nondisclosure agreement that would have prevented her from discussing their alleged sexual affair.

On Wednesday, Sanders told reporters that the arbitration was won "in the president's favor." The statement is an admission that the nondisclosure agreement exists, and that it directly involves the President. It is the first time the White House has admitted the President was involved in any way with Daniels.

"POTUS is very unhappy," the source said. "Sarah gave the Stormy Daniels storyline steroids yesterday."

Trump's personal lawyer has said the President "vehemently denies" any sexual encounter between the two.