The next election is more than 15 months away, but the first campaign field office is already open and buzzing with activity in the politically high-priority Third Congressional District of Minnesota.

It wasn't opened by any of the candidates. The Congressional Leadership Fund (CLF), a deep-pocketed national super PAC that has poured millions into Republican races already this year, recently opened a Minnesota outpost at a nondescript strip mall in southwest Bloomington. It's home base for teen volunteers who make calls and knock on doors across the district's suburban neighborhoods, urging voters to send U.S. Rep. Erik Paulsen back for a sixth term next year.

Neither Paulsen nor any of the DFLers hoping to unseat him have opened campaign offices in the Third, which encompasses parts of Bloomington, Eden Prairie, Minnetonka, Edina, Brooklyn Park and other southwestern suburbs. The district was one of just a handful nationwide that supported Democrat Hillary Clinton for president last year but also elected a Republican to Congress, and national Democrats hoping to capitalize on unease with President Trump are expected to go after incumbents like Paulsen next year.

That's where the CLF comes in. Its low-key Minnesota operation, run by a single paid staffer, represents a seismic shift in the campaign landscape. A political action committee — capable of raising and spending limitless amounts of money — is donating not just dollars to a race, but manpower and a physical presence in the district. And it's doing it a year and a half out from Election Day.

"There's no off season anymore," said CLF Executive Director Corry Bliss, whose group has set up a dozen brick-and-mortar campaign offices in at-risk Republican districts around the country.

Flooding the zone

On Tuesday, 10 young men and two young women sat at tables arranged in a square, each with an assigned phone and list of numbers. They dialed until they got someone on the phone, then read through a script: "I'm calling from the Congressional Leadership Fund, and wondering if you would participate in a short survey that will only take one minute."

Few callers seemed interested in participating. Those who did were asked about their support for Trump and about the issue they think is most important to the country.

Chelsea Montgomery, 18, a recent high school graduate from Bloomington, found out about the CLF's phone-banking and door-knocking efforts from her school counselor. She's planning to minor in political science, so she figured it would be a useful addition to her résumé.

Montgomery spends about five hours a day making calls and knocking on doors. No one has slammed a door in her face, and some actually seem eager to talk, she said.

"I think it helps for people to know that young people are interested in politics," she said.

The CLF's pitch for Paulsen highlights his stand on bipartisan, unifying issues — legislation he's sponsored to fight human trafficking, and his work with Democrats to combat the opioid crisis. Bliss said engaging with voters now is more effective in some cases since CLF isn't competing with the blitz of campaign ads and mailers in the final weeks before an election.

The CLF raised more than $50 million for candidates last year, and poured $10 million into this spring's special elections, replacing four departing congressional Republicans with four new Republicans despite unexpectedly strong Democratic challenges in Georgia and Montana.

Now the group is taking those tactics nationwide, with plans to open as many as 30 field offices by the end of the year. Donations are pouring in from corporations, wealthy individuals and interest groups like former Minnesota Sen. Norm Coleman's American Action Network, which has chipped in more than $7 million already this year.

In an era where campaigns are driven by polls and data, Coleman sees value in the labor-intensive work of doorknocking an entire district. All the voter data in the world won't help if you can't get those voters to the polls.

"We want to win," Coleman said. "We're a great believer in personal contact and having folks on the ground, having them knock on folks' doors. ... We decided to put some muscle into it, put some resources into it."

The donors giving to Coleman's nonprofit "have a lot of questions about the value of a 30-second commercial," Coleman said. But when it comes to seeding a grass-roots network in a shaky district, "they get it."

'The world is changing'

Traditional campaigning, where candidates save their pennies for a big TV advertising blitz in the month or so before Election Day is "a really old, and really lazy, model," Bliss said. "I think the world is changing."

While no other super PACS have set up shop in Minnesota — yet — others are already homing in on their targets. EMILY's List, which backs female Democratic candidates who support abortion rights, recently announced it was setting sights on Minnesota's Second Congressional District and freshman Republican U.S. Rep. Jason Lewis — one of 48 districts it's hoping to flip.

"That district is very much in play this cycle, and we're targeting it as part of our largest-ever Republican opposition effort," spokeswoman Alexandra De Luca said.

Paulsen's most high-profile DFL challenger, businessman Dean Phillips, is keeping a wary eye on the soft money avalanche rolling into the Third District.

Campaign manager Zach Rodvold said he hadn't heard of any Democratic super PACs investing in this level of campaign infrastructure but wouldn't be surprised to see it in the coming months given Minnesota's contested congressional map.

"It's no surprise that a special interest-funded super PAC has made it a top priority to support a special interest-funded politician like Erik Paulsen," Rodvold said in a statement.

Strings attached

CLF attack ads — featuring ominous, grainy footage of Nancy Pelosi and comedian Kathy Griffin posing with a gory severed Trump head — have been popping up online, hitting Democratic candidates in targeted districts across the country. The group hasn't started airing Paulsen ads.

CLF field offices tailor their pitches to individual districts, Bliss said. But super PACs don't offer unconditional support. The CLF expects its candidates to take tough votes on issues like health care. Paulsen voted to repeal the Affordable Health Care Act. When Iowa Republican Rep. David Young announced he would vote against the replacement House health care bill, the CLF closed its office in his district.

The Paulsen campaign is aware of the CLF's efforts, but candidates are banned by law from coordinating with special-interest groups.

"Millions in outside money were spent last cycle and I suspect the same will happen again," said the Paulsen campaign's John-Paul Yates.

The president's party usually loses seats in Congress in midterm elections. Hundreds of Democratic challengers are running in 2018. In the Third District Phillips raised more than half a million dollars in the six weeks after he launched his bid to unseat Paulsen, almost matching the incumbent's fundraising that quarter.

"The national Democrats have made it very clear that he's one of their top targets," Bliss said. "We have one mission, and one mission only, and that's to help win the tough House races. We look at races where we can invest time and resources and make a difference."

erin.golden@startribune.com 612-673-4790

jennifer.brooks@startribune.com 202-662-7452