Sean O'Brien, Teamsters union chief, becomes first Teamster to address RNC

Sean O'Brien, president of the International Brotherhood of Teamsters, gave Monday's keynote speech at the Republican National Convention, delivering one of the most anti-big business speeches in recent RNC memory and becoming the first boss in the organization's 121-year history to address the convention.

The Teamsters, which hasn't endorsed a candidate so far in 2024, has endorsed Democrats in recent years. But as the Republican Party's rhetoric has grown more populist, O'Brien was invited to speak at the RNC as Republicans vie for union votes. O'Brien said he doesn't believe in "knee-jerk" union loyalties.