In battleground Wisconsin, both the presidential election and the Senate contest will be a true test of the ability of the competing campaigns to energize voters weary after last summer's rancorous recall vote.
The Nov. 6 election also stands as a tie-breaker on Wisconsin's political identity.
The state overwhelmingly backed President Barack Obama in 2008 but two years later elected Republican Scott Walker as governor and chose tea party-backed Ron Johnson over incumbent Democratic Sen. Russ Feingold.
The Senate race between former GOP Gov. Tommy Thompson and seven-term Democratic congresswoman Tammy Baldwin will help determine which party controls the Senate.
Strong voter turnout in increasingly Republican northeast Wisconsin would be needed to offset the heavy Democratic vote in more populous Dane County and the state capital of Madison.