An Air Force veteran who has been imprisoned for nearly three years for leaking a classified report on Russian hacking while she was an intelligence contractor applied for clemency from President Trump on Monday.

The contractor, Reality L. Winner, 28, petitioned the Office of the Pardon Attorney, which is part of the Justice Department, to commute the rest of the 63-month sentence that she received in 2018.

A lawyer for Ms. Winner submitted more than 4,500 letters of support from members of the public with the application. During a news conference in Dallas on Monday, Ms. Winner’s family said that they hoped the materials would prompt Mr. Trump’s intervention in the case.

At the time of Ms. Winner’s sentencing, Mr. Trump said on Twitter that the punishment was “unfair” and that what Ms. Winner had done was “small potatoes compared to what Hillary Clinton did.”