The battle for Senate control could rest with voters in just 10 states, according to where political groups have committed tens of millions of dollars in political advertising for the midterm campaign’s final week.

Republicans have to flip six Democratic-held seats on Nov. 4 to win the majority, and they’re poised for three easy pickups. But Republicans are hunting for those next three crucial victories in seven of the 10 states where this high-stakes, high-dollar battle is being waged: Alaska, Arkansas, Colorado, Iowa, Louisiana, North Carolina and New Hampshire. Except for Iowa’s open seat, each race features a Democratic incumbent running for re-election.