 The delegation formally nominated him yesterday on the opening day of the RNC in Milwaukee. A jubilant Vance pumped his fists in the air when it became official. The Ohio senator is relatively new to politics, but known as a strong MAGA supporter, he's due to address the Republican National Convention later this week. The president of the International Brotherhood of Teamsters says American families know the system is broken. Sean O'Brien made history as the first head of the union to address the Republican National Convention.