Rep. Alexandria Ocasio-Cortez of New York, left, and Teamsters President Sean O'Brien.Justin Sullivan/Getty Images; Kevin Dietsch/Getty ImagesThe Teamsters last week declined to endorse a candidate in the 2024 presidential race.It's a stunning decision given Kamala Harris' strong pro-union stance on key issues.AOC called into question the leadership of Teamsters president Sean O'Brien.The Teamsters last week declined to back Vice President Kamala Harris or former President Donald Trump, marking the first time since 1996 that the union has not endorsed a presidential candidate.It came as a shock to many Democrats.