WASHINGTON — Mary Rafferty got married in June, but she’s delaying her honeymoon until after Election Day for a not-so-tropical getaway: an air bed in Denver that lets her knock on doors in support of Democrat Mark Udall and his re-election campaign.

Walking a similar beat is Rudy Zitti, a former Long Island police officer who’s making the rounds for the conservative group Americans for Prosperity and its goal of limited government.

The two activists are among the hundreds of political foot soldiers expected to flood Colorado neighborhoods ahead of the Nov. 4 election.

While invasions of this kind are nothing new, several factors are converging on Colorado this year that could make the state home to the fiercest “ground war” in the country.

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Not only does the Centennial State feature three high-stakes races — for governor, the U.S. Senate and a U.S. House seat — but the state’s new liberal voting laws invite huge spending on get-out-the-vote efforts across the political spectrum.

Traditional campaigns now are competing for doorstep time with third-party groups focused on issues ranging from health care and the federal debt to conservation and reproductive rights.

And it’s not a last-minute effort either.

Rafferty, 29, already has visited the homes of hundreds of Colorado voters; Zitti, 68, said he is in the thousands now. And both say their conversations with average Coloradans could turn the tide this election year.

“Yes, some people slam the door in your face,” said Zitti, who now lives in Colorado. “(But) face-to-face engagement with people is what I really think is the key to pushing Americans for Prosperity’s message.”

Added Rafferty, who is with the pro-Udall group Colorado Fair Share: “This is the most important thing I could be doing. It’s a really critical election.”

Rafferty is not alone in that assessment — at least if political advertising is any indication. More than $60 million has been spent this year on TV ads alone in the state, according to researchtabulated by journalist Sandra Fish for Colorado Public Radio.

And that figure doesn’t include the millions of dollars that outside groups and the political parties have pledged to sink into get-out-the-vote operations in Colorado.

While the overall cost of these efforts is difficult to determine, the expectation among state politicos is that 2014 could be a record-setting year for the amount of money devoted to grassroots efforts in a nonpresidential election.

“There’s a larger investment in the ground game as opposed to four years ago,” said Steve Fenberg, executive director of the get-out-the-vote group New Era Colorado.

While candidates and political parties have been active before, he said “it seems like there are a lot more independent players.”

Cost-effectiveness

One potential explanation is that get-out-the-vote operations are much cheaper than television and, given advances in campaign record-keeping, canvassers can focus their attention on the homes of likely supporters.

“To put all your eggs in the broadcast basket means that hundreds of thousands of voters won’t hear your message,” said Mitch Stewart, who led the effort in so-called “battleground states” for President Barack Obama during the 2012 campaign.

Rudy Zitti, a former beat cop from Long Island who now works for Americans for Prosperity, goes door-to-door handing out informational flyers and talking

Rudy Zitti, a former beat cop from Long Island who now works for Americans for Prosperity, goes door-to-door handing out informational flyers and talking to voters in Loveland on Sept. 10, 2014. (RJ Sangosti, The Denver Post)

Now consulting with the Environmental Defense Fund, Stewart is part of the group’s $2 million drive this year to get 100,000 Colorado residents to pledge to vote.

“The goal is to increase turnout with a specific group of millennials” who care about climate change, he said. And if this “test run” of voter “data targeting” is successful, officials with the Environmental Defense Fund said they plan to replicate the effort nationwide.

“If you want to be impactful as an organization, you have to use 21st-century tactics,” Stewart said.

A similar calculation is being made by Americans for Prosperity, the political heavyweight backed by billionaire industrialists Charles and David Koch.

“We’re trying to build a grassroots army,” said Dustin Zvonek, head of the group’s Colorado affiliate. A giant in the political world, Americans for Prosperity is no stranger to television — having run TV ads in Colorado as early as last October.

But Zvonek said reaching like-minded voters — and getting them to vote — is the real key to winning elections.

“The hard work, but the most important work, is the ground effort,” Zvonek said. With a team of roughly 35 members, the state chapter of AFP is “knocking on 10,000 doors every week in Colorado,” he said.

When they do, staff members often use a four-question survey to determine voters’ views toward federal spending and the Affordable Care Act, popularly known as “Obamacare.”

It’s the health care question that Zvonek said ultimately could produce the biggest payoff with Colorado voters.

“Opinions on Obamacare are not strong,” he said. “We really have an opportunity to educate them more.”

Early voting

There’s plenty of time to make an impact, too. Colorado has a lengthy early-voting period, which begins in mid-October.

“We don’t have an Election Day anymore,” Zvonek said. “We have an Election Deadline.”

He added that his team is planning a “mad scramble” to knock on doors once the state sends out mail-in ballots — as this year will be the first major election in which every active Colorado voter will get one.

Many of these homes will house the same voters who took the four-question survey for Americans for Prosperity.

“Inevitably, there are a lot of ballots that will be tossed in the trash,” Zvonek said. “We’re trying to minimize that.”

Another new wrinkle for the general election season is that Colorado residents now can register to vote and cast a ballot on the same day, thanks to a Democratic-backed law passed in 2013.

“The fact that Colorado makes it easier for its citizens to vote was one of the factors we looked at in choosing the state for this project,” said Keith Gaby, a spokesman for the Environmental Defense Fund.

While the group aims to motivate a specific kind of voter, it’s not officially targeting any candidate or race.

That’s not the case for another environmental group: NextGen Climate. The new organization, backed by billionaire investor and eco-activist Tom Steyer, is taking direct aim at U.S. Rep. Cory Gardner, the Republican challenging Udall.

Not only is NextGen Climate buying TV ads against Gardner, but it’s also launching a major canvassing effort. With a crew of at least 68 workers, the group is “targeting a universe of 88,000 voters living in the Boulder and Denver metro areas,” according to a strategic “blueprint” released by the organization.

Craig Hughes, a consultant for NextGen Climate in Colorado, said the group aims to have “significant investment” on television but a “bigger investment in on-the-ground operations.”

“At some point there are diminishing returns on TV,” he said.

The Internet

In trying to build these election-year armies, outside groups are turning to Craigslist and other mediums to attract staff members. At least four groups recently posted ads on Craigslist in Boulder to recruit canvassers and other campaign workers.

How much these standing armies, or Colorado’s new voting rules, will affect turnout remains an open question — and one that could determine who wins the Udall-Gardner race and which party controls the Senate next year.

Driving up turnout is especially important for Democrats, who historically lose supporters during elections in which the presidential race is not on the ballot.

The lack of participation is especially pronounced among non-white voters, unmarried women and Americans younger than 30, according to forecasts released by the Voter Participation Center, an advocacy group devoted to increasing turnout by these groups.

Although Colorado is split almost in half between voters who fit these three categories and those that do not, the group estimates that a much larger percentage of single women, non-white voters and the young won’t go the polls this year.

In raw numbers, about 361,000 Democratic-leaning voters in Colorado are not expected to cast a ballot this year, compared with about 293,000 truants who are more likely to support the GOP.

Adding to Democratic woes are Obama’s low poll numbers, which suggest a significant uphill climb for his party and its allies.

To compensate, Colorado Democrats are trying to replicate successful get-out-the-vote efforts used by Obama in 2012 and now-U.S. Sen. Michael Bennet in 2010, who also brings the support of the Democratic Senatorial Campaign Committee he chairs.

Udall’s campaign and the DSCC teamed up last month, for example, to hit Gardner with a Spanish-language ad.

“This will be far and away the biggest midterm effort that Colorado has ever seen,” said Chris Harris, a Udall spokesman.

Harris said the Udall campaign, with help from the state party, has the goal of registering 100,000 Colorado voters with an outreach effort of 8,000 to 10,000 volunteers.

Polls have shown the Senate race is neck-and-neck. But Republicans say Democrats are overpromising, and they argue evidence of a GOP advantage can be seen in the state’s voter rolls.

As of Sept. 1, there were roughly 57,000 more registered Republicans in Colorado than registered Democrats. Last year the GOP’s edge in registration was about 28,000 — roughly half that.

“We’re doing a better job of keeping our folks engaged than they are,” said Michael Short, a spokesman for the Republican National Committee. He said the RNC has put staff in Colorado for more than a year and that the outreach is part of a national $100 million investment in get-out-the-vote operations.

Short also said Republicans have invested heavily in shoring up the technology side of campaigning to narrow — or even overcome — the advantage Democrats have enjoyed in recent years.

Television ads

The focus on grassroots organizing, however, hasn’t sated the appetite for television advertising. The $60 million in political ads bought so far this year would “fill 25 straight days of viewing,” according to Fish’s research on Colorado Public Radio.

Those purchases are almost evenly divided between Democrats and their allies and Republicans and their supporters — with Democrats slightly ahead with nearly $28.6 million in spending versus roughly $26.2 million for Republicans. Unaffiliated groups make up the remaining $5.5 million.

“They all seem to want those television ads more than anything,” said Craig Holman, an expert on campaign-finance reform with the liberal advocacy group Public Citizen.

He said fears about the potential for bombarding voters with ads — in that they start to tune them out by Labor Day — hasn’t registered with political consultants or campaigns.

“I swear only political scientists realize it,” he said.

The sheer amount of money involved has been made possible thanks to recent court rulings that have loosened rules on spending. The flood of cash since then has prompted Holman and others to raise concerns about whether special interests are taking over U.S. elections.

In the 2012 election, outside groups — not including candidates or the political parties — spentmore than $1 billion trying to sway voters, according to the Center for Responsive Politics.

Some of these are well-known, such as Americans for Prosperity, which was part of $719 million in spending for conservative groups, compared with about $293 million for liberal groups that year.

Spending rules

In response to the flood of money, federal lawmakers have proposed putting some kind of limit or rules on the spending — or at least require more disclosure from the outside groups that engage in the political process. But these efforts have stalled, and there’s little expectation that they will advance anytime soon.

All of which means that the waves of activists canvassing in Colorado this year could became a permanent campaign fixture — and that’s not necessarily a bad thing, said one outreach organizer.

Wendy Wendlandt, the national director of Fair Share, compared the attitude of Colorado residents to those living in another bellwether state in the middle of the country.

“It’s become a little bit like Iowa,” she said. “Everyone (in Colorado) cares deeply about being talked to and they expect to be talked to.”

And so, she said, her group plans to establish offices across the state that will serve as a home base for workers such as Rafferty who are trying to bring a “simple message” to voters across the state.

“This is a human on your doorstep who cares about these issues,” she said. “And you should, too.”

Mark K. Matthews: 202-662-8907, mmatthews@denverpost.com or twitter.com/mkmatthews