More than a week after Election Day, control of the House of Representatives has yet to be decided. Out of the 435 seats in Congress’s lower chamber, 12 have yet to be called. How many of these seats — most of them concentrated in slower-counting Western states such as California and Arizona — does each party need for a 218-seat majority?

Republicans are on the brink of maintaining their House majority—and winning control of Washington for at least the next two years under a unified government—with 11 races left to be called as of Wednesday.