Sen. Michael Bennet, D-Colo., faces a primary challenge in Tuesdays elections in his state. File Photo by Sarah Silbiger/UPI | License Photo

June 30 (UPI) -- Colorado voters must turn in their ballots by 7 p.m. MDT Tuesday in the state's primary elections to have their vote count in several hotly contested races.

Up for grabs are the governor, secretary of state, U.S. Senate and eight House of Representatives seats, plus state offices. The deadline to mail ballots has already passed, so voters must hand-deliver their votes to one of the state's 137 voting centers or 437 drop boxes.

More than 783,000 ballots were returned by Tuesday morning, CBS News reported. Voters ages 65 and older have returned 27% of the ballots, with ages 18-24 and 25-34 having ] about 10% of their ballots returned.

Democrats have returned 52% of the ballots and Republicans 35%. The rest have been listed as Libertarian, Unity or other third parties.