WASHINGTON – National political spending groups have deluged Minnesota with more than $29 million in four key U.S. House races, a potent symbol of the state's importance to the battle for control the U.S. House in November.

In northeast Minnesota's open Eighth District, one of the Republican Party's best chances nationwide to pick up a seat now held by a Democrat, outside conservative groups have dramatically offset Democrat Joe Radinovich's fundraising advantage. He's raised $1.5 million, while Republican Pete Stauber has raised $1.4 million. But outside organizations have spent $7.3 million to target area voters, much of it on ads critical of Radinovich.

The largely rural district, which includes Duluth and the Iron Range, is currently represented by Democratic U.S. Rep. Rick Nolan, who is stepping down. President Donald Trump won it by nearly 16 percentage points in 2016.

Three other districts join the Eighth in generating intense interest. In the mostly suburban Second and Third districts, Democrats are aiming to unseat Republican incumbents; Republicans hope to flip another Trump district, southern Minnesota's First. Democrats need to pick up 24 seats to take back the House.

Candidates themselves in those four districts have raised another $23 million as they seek to woo voters with mailers, ads and campaign stops, according to a Star Tribune review of federal election reports released this week.

"If it weren't for the millionaires and billionaires coming out to buy this congressional seat for Pete Stauber, we would be winning this race in a landslide — instead we're fighting uphill," Radinovich said, maintaining that he was being targeted because he would not prioritize tax cuts for the wealthy over infrastructure, health care, college affordability and retirement security.

The Congressional Leadership Fund spent $3.9 million against Radinovich, while America First Action spent $1.9 million; both are conservative groups. The Democratic Congressional Campaign Committee put forth $1.2 million in support of Radinovich.

The conservative groups have run ads attacking Radinovich on matters both personal and political, leaving Stauber to spend his own ad dollars touting his merits.

"Pete continues to focus on the issues that matter most to the Minnesotans in the Eighth District and has run a positive TV ad campaign that highlights his life experiences which help shape his character and values as a husband, father of four children, and a 23-year law enforcement officer," said Caroline Tarwid, a spokeswoman for Stauber's campaign.

Biggest spending in Third

The biggest spending by candidates and outside groups combined is in the southwestern metro suburban district represented by U.S. Rep. Erik Paulsen, a five-term Republican battling Democrat Dean Phillips, a businessman. Outside groups have spent $9.1 million in the Third District, more than half to oppose Phillips. Nationwide, that puts it seventh in the nation for outside spending on House races, according to the Center for Responsive Politics.

Phillips has decried the influence of money in politics as a top campaign theme. He was the sole beneficiary in Minnesota of spending by End Citizens United, an independent expenditure group that aims to elect members of Congress who will work to overturn the Supreme Court's Citizens United decision allowing unlimited spending from organizations independent of campaigns. The group spent $100,000 against Paulsen and $653,976 for Phillips.

Paulsen is hardly in a vulnerable financial spot: He's raised $5.1 million this cycle, more than any other House member in Minnesota, while Phillips took in $4 million. Paulsen, the state's senior Republican in Congress, holds a coveted spot on the House Ways and Means Committee and the chairmanship of the Joint Economic Committee, a bipartisan panel that advises Congress on economic matters.

On Friday, the Phillips campaign attacked Paulsen for becoming the fourth-largest recipient of political action committee funds in Congress, according to new federal disclosures. And the Phillips campaign complained that GOP-aligned groups had "gone nuclear" with negative advertising.

Phillips aside, Democratic candidates in Minnesota's most-competitive races have raised more money than their GOP rivals. In the Second District, southeast of the Twin Cities, former health care executive Angie Craig has raised more than any other Democrat in Minnesota's top House races: $4.2 million. Her opponent, U.S. Rep. Jason Lewis, a first-term Republican, has raised $2.5 million.

The majority of the $5.3 million in outside spending in the Second District has been on Craig's behalf. The Giffords PAC spent $1.3 million against Lewis for not voting for stronger gun control polices.

The Lewis campaign this week labeled Craig a hypocrite for promoting the importance of getting money out of politics even as she outraises him and benefits more from outside groups. A Lewis campaign news release said he was facing attacks from what it called "far-left, dark money groups" backing Craig, including Planned Parenthood and the Environmental Defense Fund's EDF Action.

In individual contributions over $200, Craig has received 55 percent from out of state, largely from New York, Boston and San Francisco. Lewis has gotten 35 percent from out of Minnesota, mainly from the District of Columbia, Houston and Denver.

Lewis and the National Republican Congressional Committee have repeatedly hammered Craig as beholden to the medical device industry; Craig was second to only Hillary Clinton in receiving donations from those interests in 2016. But this election cycle, Craig did not make the top 20. Paulsen remains the third-largest recipient of donations from the medical device and supply industry, at $83,950.

In southern Minnesota's First District, Democrat Dan Feehan raised $3.1 million — about three times as much as Republican Jim Hagedorn. But another $7.9 million is flooding the district, roughly evenly split between the two candidates.

Feehan, a veteran of the Iraq war, got a $989,030 boost from VoteVets.org, along with $156,507 from the With Honor Fund.

The Congressional Leadership Fund spent $6.7 million in Minnesota, including $2.9 million against Phillips, while the Democratic Congressional Campaign Committee spent $4.7 million, mostly in support of Feehan and Radinovich and against Lewis. The National Republican Congressional Committee spent $6.5 million against Feehan, Craig and Phillips.

On Thursday, that group released an ad portraying Feehan as beholden to liberal billionaire George Soros and linking him to left-wing rioters and "prima donna athletes protesting our anthem," showing NFL quarterback Colin Kaepernick on bended knee. Feehan is an Army veteran who served two combat tours, earning him a Bronze Star and other commendations.

Maya Rao • 202-662-7433