Ronald N. Weiser is an American businessman and Republican Party activist, donor and financier. Weiser founded a real estate company. He held fundraising roles for the presidential campaigns of George W. Bush and John McCain. He was chairman of the Michigan Republican Party from 2009–2011, 2017–2019, and 2021–present. He was U.S. ambassador to Slovakia during the Bush's first term (2001–2004) and was elected to the Board of Regents of the University of Michigan in 2016.