Americans for Prosperity, a conservative group backed by the Koch brothers, is launching a campaign Wednesday to aid the reelection bid of Rep. Mike Coffman, a Colorado Republican — the first time the group is devoting concerted grass-roots efforts to influence the outcome of a House race in the 2016 general election.

The campaign does not include paid media, but the group will send out hundreds of staffers to knock on doors in Colorado’s 6th Congressional District, which includes Aurora and other segments of suburban Denver, to urge constituents to vote for Coffman over his Democratic challenger, state Sen. Morgan Carroll, in what could be a tight race.

While the chances of Republicans maintaining control of the House in this year’s election remain high, Democrats are more optimistic they have a shot at regaining the majority, under the belief that the controversial campaign of presumptive GOP presidential nominee Donald Trump could harm down-ballot Republican candidates.

Conservative and GOP-aligned groups are also taking note of what could be an unusual election year and are expressing concerns about a Democratic takeover.

“It’d be a disaster for our nation if Nancy Pelosi and House Democrats possess a majority next January given their support for higher government spending, higher taxes and new restrictions on our First Amendment freedoms,” said Tim Phillips, president of Americans for Prosperity.

The aim in Colorado is to help preserve the Republican majority by targeting districts where AFP already has staff and resources and can most efficiently affect voting outcomes, according to the group. Dustin Zvonek, regional director for AFP, worked on Coffman’s first congressional campaign.

Coffman was elected in 2008. His 2016 reelection is considered a toss-up that tilts slightly in his favor, according to the nonpartisan Rothenberg & Gonzales Political Report. Stuart Rothenberg is a PowerPost contributor.

Coffman maintains a fundraising advantage over Carroll. During the first three months of 2016, he raised $352,000 and had $1.3 million in cash on hand. Carroll raised $333,000 and had $641,000 in cash on hand, according to Federal Election Commission reports.

AFP has already launched similar advocacy efforts on the Senate side in Pennsylvania, Ohio and Wisconsin, but Coffman’s race is the group’s first foray into a general-election House race this cycle. The group may target more races in the near future.

AFP estimates it will devote six figures to the campaign in Colorado, including phone and digital outreach, temporarily relocating field staff from other Western states to the Denver area and recruiting volunteers.

The efforts will be similar to those that AFP undertook recently in North Carolina’s 2nd Congressional District, where it launched a six-figure TV ad buy and a grass-roots operation to defeat Rep. Renee L. Ellmers, a Republican, in a June special primary election held as a result of redistricting. Rep. George Holding (R-N.C.) won the primary with 53 percent of the vote; Ellmers finished second, barely beating out Raleigh physician Greg Brannon. AFP argued that Ellmers’s voting record was less conservative than she promised it would be when she was elected in 2010.

Carroll’s campaign manager, Jennifer Donovan, called AFP an “unaccountable and extremist group.”

“The last person that the Koch brothers want to see in Congress fighting on behalf of hard-working Coloradans is Morgan Carroll,” she said.”Morgan has a track record of fighting dark money in politics, and that is not something Americans for Prosperity is interested in.”

Correction: An earlier version of this post misspelled the name of AFP’s Dustin Zvonek.