WASHINGTON – A week before Election Day, more than 8 million people in some 30 states have already voted, an early warning sign to the major parties of states where they're doing well and where they're already falling behind.

With control of the Senate hinging on 10 close races, the major political parties and their aligned groups are scrambling to reach supporters who haven't cast ballots yet.

"You run a risk if you don't connect with early voters now," said Bill Carrick, a Democratic strategist.

In Georgia and North Carolina, about 22 percent of this year's early voters have no record of voting in the 2010 midterm elections, according to Michael McDonald, a University of Florida political science associate professor.

Early voting has produced mixed results heading into next Tuesday's election.

In Iowa, where Republican Joni Ernst and Democratic Rep. Bruce Braley are vying for the open Senate seat, Republicans last week trumpeted figures showing them outpacing Democrats in early votes for the first time in two cycles.

In Colorado's Senate race, where Democratic Sen. Mark Udall is in a tight race with Republican Rep. Cory Gardner, Republicans last week returned 145,824 mailed ballots to the Democrats' 105,401 ballots, election officials said.

Of the 660,113 overall early votes in Colorado, about 43 percent were cast by Republicans, 32 percent by Democrats and 25 percent by voters listed as "none or other." Coloradans exclusively vote by mail.