Returned ballots from Colorado voters topped 2 million at mid-afternoon Tuesday and reached 2,217,895 by 6 p.m. MT, with Colorado Democrats maintaining their ballot lead over Republicans, the Secretary of State’s office announced.

As of two hours before the polls closed, a total of 2,217,895 ballots had been received and validated by election officials, out of more than 3.3 million sent to voters. Of those, 732,700 were from Democrats, 725,464 were from Republicans and 728,004 were from unaffiliated voters.

It’s too late to mail ballots, which must be received by 7 p.m. Tuesday in order to count, election and U.S. Post Office officials say. Ballots can be dropped off in person until 7 p.m. Tuesday or you can vote in person; find out where at GoVoteColorado.com.

ELECTION NIGHT 2018: Check back with ColoradoPolitics.com after the polls close for full results.

Overall, turnout is up from the last midterm election – 1,607,220 ballots had been received at the same point in 2014 – but it isn’t evenly distributed. Democrats and unaffiliated voters have been voting in much higher numbers than they did four years ago, while Republicans are lagging.

At this point in the last midterms, 18,000 more Republicans had already voted, while 108,000 fewer Democrats had gotten their ballots in, and more than 150,000 fewer unaffiliated voters had cast their ballots.

Among Democrats and unaffiliated voters, ballot returns by younger and first-time voters are surging, according to an analysis by Magellan Strategies, a GOP firm.

While the number of ballots cast by Colorado Republicans under 45 has dropped by several thousand since the last midterms, the number of Democrats and unaffiliated voters under 45 who have already voted has jumped – around 70,000 more younger Democrats and around 80,000 more younger unaffiliated voters.

The number of first-time Republican voters at this point is roughly the same as it was four years ago, but the number of first-time Democratic and unaffiliated voters has more than doubled, Magellan’s analysis found.

Republicans have been sounding the alarm about their party’s early vote performance for weeks, since initial returns showed substantially lower rates since the last midterm.

On Tuesday, Colorado GOP chairman Jeff Hays sent an ultimatum to supporters in an email: “Today we either close that gap or surrender our state to the most radical Democrats their party has ever nominated.”

Democrat Jared Polis and Republican Walker Stapleton are vying to be Colorado’s next governor.

Voters will also decide one of the most hotly contested congressional races in the country, in the suburban 6th Congressional District where five-term Republican U.S. Rep. Mike Coffman is running against Democratic challenger Jason Crow, an attorney and first-time candidate.

A handful of state Senate seats are also in play as Republicans try to keep their one-vote majority in the chamber.