<Tr> <Td> Norman E. Mack </Td> <Td> 1908--1912 </Td> <Td> New York </Td> </Tr> <Tr> <Td> William F. McCombs </Td> <Td> 1912--1916 </Td> <Td> New York </Td> </Tr> <Tr> <Td> Vance C. McCormick </Td> <Td> 1916--1919 </Td> <Td> Pennsylvania </Td> </Tr> <Tr> <Td> Homer S. Cummings </Td> <Td> 1919--1920 </Td> <Td> Connecticut </Td> </Tr>

Who elects the chairperson for the republican and democratic national committees