It was a system designed and pushed through by a Democratic legislature. And coincidentally: it's a system that, wherever it's been introduced, has almost always advantaged Democrats.
But not this year. So far, Republicans are ahead in Colorado.
As of Oct. 31, just over 1.1 million people have mailed in their ballots. About 465,677 of them, or 41 percent, are from Republicans. Democrats have mailed in 371,190 ballots, or 32 percent and unaffiliated voters have sent in 290,600 ballots, 25 percent of the total.
“It’s sort of a faceless election where you don’t have that human interaction. It’s going to be delivered by the mail,” said Secretary of State Scott Gessler, a Republican who opposed the change in law.
"I'm completely against the same-day voter registration system," Gessler said, though he is enforcing it. "You do it the best you can. We pride ourselves in Colorado in having one of the best-run election shops in the country and we intend to keep it that way."
Colorado has always had a robust vote by mail and early voting operation, as large parts of the state are incredibly rural. Here in Buena Vista, a town of about 2,700 people ringed by snow-capped peaks and bluebird skies, the push to get people to vote early is in full effect.
But in places like Buena Vista, a town about 94 miles west of Colorado Springs, the call has now shifted from telling people to drop their ballots in the mail to telling them to drop them off at voter service centers. Mail-in ballots must be shipped to Denver and then back to the county where they originated so the signatures on them can be verified by an election judge and they can be counted. With less than a week to go before Election Day, there is worry that the mail will be too slow from far-flung places like this.
"It is too late to put your ballot in the mail. It must be dropped off," Carolyn Riggs, a field organizer for Sen. Mark Udall's re-election campaign said at a rally at a coffee shop here. Udall arrived with Sen. Michael Bennet on a massive bus in which is is touring Colorado. Clad in jeans and brown cowboy boots, Udall had a button reading "VOTE OR DIE!" affixed to his blue fleece jacket.
"Can you read my button?" Udall asked the enthusiastic crowd gathered on a patio.
"It cannot be postmarked and be counted. It has to be in the elections office," Riggs said. Ballots must be in the local elections office by 7 p.m. Tuesday. "It is so crucial that we get every one of our Democratic votes in there so we can re-elect this guy," she said, gesturing toward Udall.
In a state filled with close, contentious races, urging voters to vote early is the one thing both parties have in common.
"How many of you have already voted? Put your hand up proudly, but your hand up," Udall's competitor, Republican Rep. Cory Gardner, asked a crowd gathered at Douglas County fairgrounds in Castle Rock Wednesday. The majority of hands in the crowd, gathered in a ring used to show livestock and where hay bales were set up as seats, shot up. "Now here’s the real test. Who hasn’t voted? Now it’s peer pressure time. You know who they are. Get their names. We need your votes. Colorado has the opportunity to be the tip of the spear, the vanguard of a movement."
Rather than set up polling stations at schools or community centers in neighborhoods or wards, as is typically the case around the country, Colorado has “voter service centers” at various places in each county – they’re kind of like DMV branches. Residents can cast ballots at any service center in the county and also register to vote at them.
Here in Buena Vista, a slender metal box reading "Chaffee County Official Ballot Drop Box" stands near the front door. There is also an election center in the back, where two boxes sat atop a table Friday: one where voters could drop mail-in ballots, another where they put ballots they fill out at one of three tables at the center.
Three election judges -- two Republicans and one Democrat (there must be at least one of each party) -- waited for voters to come in. All voters who cast ballots at polling places must provide identification.
Amy Eckstein, 38, made a mistake on the ballot she received in the mail, so she brought it in and got a ballot here.
"It's great," she said, but refused to disclose for whom she voted. "Anything to increase voter turnout is a great way to go."