More than three decades ago, when [Jessica Leeds] was a traveling businesswoman at a paper company, Ms. Leeds said, she sat beside Mr. Trump in the first-class cabin of a flight to New York. They had never met before.

About 45 minutes after takeoff, she recalled, Mr. Trump lifted the armrest and began to touch her.

According to Ms. Leeds, Mr. Trump grabbed her breasts and tried to put his hand up her skirt.

“He was like an octopus,” she said. “His hands were everywhere.”

She fled to the back of the plane. “It was an assault,” she said.