President-elect Donald Trump has expressed a keen interest in privatizing the U.S. Postal Service in recent weeks, three people with knowledge of the matter said, a move that could shake up consumer shipping and business supply chains and push hundreds of thousands of federal workers out of the government. Trump has discussed his desire to overhaul the Postal Service at his Mar-a-Lago estate with Howard Lutnick, his pick for commerce secretary and the co-chair of his presidential transition, the people said. Earlier this month, Trump also convened a group of transition officials to ask for their views on privatizing the...