William F. Weld, the Libertarian Party nominee for vice president, defended Hillary Clinton on Wednesday against attacks from Donald J. Trump, insisting her character should not be impugned by someone as flawed as he is.

Mr. Weld made the remarks in a brief interview with The New York Times, the latest comments he has made as part of a highly unusual move to use his remaining time in the race standing up for one of his rivals instead of making the case for his own running mate, Gary Johnson.