<P> Republican incumbent running Republican incumbent retiring Democratic incumbent running Independent incumbent running </P> <Tr> <Td_colspan="2"> <Table> <Tr> <Td> Majority Leader before election <P> Mitch McConnell Republican </P> </Td> <Td> Elected Majority Leader <P> TBD TBD </P> </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> Majority Leader before election <P> Mitch McConnell Republican </P> </Td> <Td> Elected Majority Leader <P> TBD TBD </P> </Td> </Tr> </Table> <Tr> <Td> Majority Leader before election <P> Mitch McConnell Republican </P> </Td> <Td> Elected Majority Leader <P> TBD TBD </P> </Td> </Tr>

How many senate democrats are up for reelection in 2018