What is the purpose of an endorsement in an election? Learn about how different organizations endorse candidates. Focus: the Mainstream Republicans of Washington. Founded in 1969, the Mainstream Republicans of Washington held their annual conference in May to discuss issues facing the state, endorse candidates for office, and to brainstorm how to combat divisiveness within the state. From panel discussions on the fentanyl crisis and dam removal to Building Bridges across the aisle, Republicans from across the state gathered to exchange views on how to best get Mainstream Republicans elected to office.