Tens of thousands of new Colorado voters have signed up since the start of the year — including more than 12,000 in Boulder and Broomfield counties — lured by aggressive registration drives, excitement over the presidential race and an election season that began earlier than most.

Since Jan. 1, more than 10,600 people have registered in Boulder County. In Broomfield, new voters number just over 1,700 so far this year.

Statewide, the net increase this year — taking into account new voters as well as those who died, moved or otherwise fell off the rolls — is more than 104,000. That’s almost four times the number from the same period during the last presidential election year in 2004, according to the Secretary of State’s Office.

“The excitement behind the election is something I’ve never seen before,” said Stephen Fenberg, executive director of New Era Colorado, one of more than 200 groups and individuals registered with the secretary of state to sign up new voters. “Everybody is aware of what’s going on.”

Election observers and political leaders say voter registration drives typically go into high gear in September and October. But this year is different, in part because of drives started last winter in anticipation of the February caucuses, which drew record crowds.

In late October 2004, the state had added 109,700 new voters.

“Everything is happening earlier now,” said Pat Waak, state Democratic Party chairwoman.

It’s normal for voter rolls to increase during presidential election years, then slump during off years. But Waak said interest this year is unusually high.

“We’re seeing even a bigger drive this year ... and we’re trying to take advantage of that,” Waak said.

Of new voters in Boulder County this year, 4,581 registered as Democrats, just slightly more than the number of unaffiliated voters, at 4,541. Republicans gained 1,418 new voters in the county.

Camera Staff Writer Laura Snider contributed to this report.