Democrats and Republicans have plotted for months -- and years -- to find a winning midterm strategy to control the House. But with the races now in full swing, some upsets, another ex-con candidate and a few low-profile contests have emerged to perhaps decide which party leads the chamber after November.

The Land of 10,000 Lakes

Minnesota has become a battleground state for the parties and their campaign supporters, which are putting million into several high-profile state races.

The state has eight of the total 435 House seats up for re-election -- five held by Democrats and three by Republicans. They became largely competitive and expensive this year because of Democrats’ odds of retaking the House and the state’s high-profile elections for governor and two Senate seats.

The Congressional Leadership Fund, the super PAC associated with GOP House leadership, has reserved a reported $4.9 million in TV or digital ads for Minnesota House races, while Democratic counterpart House Majority PAC has purportedly reserved $3.5 million.

Republicans see the opportunity to win at least one Minnesota House race: the 1st congressional district seat vacated by Democrat Tim Walz, who's running for governor.

The leader in GOP primary appears to be conservative blogger Jim Hagedorn, who’s competing against state Sen. Carla Nelson. Hagedorn has the state party’s backing and the personal endorsement of Minnesota GOP Rep. Tom Emmer, a co-leader in the National Republican Campaign Committee.

However, other Republicans are wary about Hagedorn’s general election chances of retaking the conservative-lean southern Minnesota seat -- considering he’s lost in three previous attempts, including a 2016 bid when Republican Donald Trump won the district by roughly 15 points.

And there’s his 2002 comment, for which he has apologized, about Democratic Sens. Maria Cantwell and Patty Murray of Washington being “underserving bimbos in tennis shoes.”

“Nominating Jim Hagedorn this cycle would be catastrophic for our chances in this seat in November,” retired Mayo Clinic Dr. Ricky Clay told Fox News on Friday. “Democrats have never spent much money or used his lengthy history of inappropriate comments against him. Trump won this district by 15 points and Hagedorn still lost. This time we have a targeted race with millions of dollars being poured into it.”

Nelson remains in one of the NRCC’s top-candidate programs and is endorsed by such groups as the anti-abortion Susan B. Anthony List.

Minnesota Democrats recently endorsed Dan Feehan as their nominee, with state primaries on Aug. 15. The nonpartisan Cook Political Report has the race rated as a “toss-up.”

Hagedorn campaign manager David FitzSimmons acknowledged Saturday that the other, bigger, races are leaving “little elbow room” for down-ticket candidates to connect with voters but said that his race is “going great” by every measure.

“The difference (now) is the outside support,” he said. “We’re building a professional campaign. … We’re already running a general election campaign.”

Traditionally With the GOP

Democrats, who must win about 24 GOP-held seats to take control of the House, face their own challenges in getting the best candidates into general elections to gain seats, particularly in Southern California.

They have targeted four GOP-held House districts in Orange County that Trump lost in 2016 to Hillary Clinton, marking the first time since the Depression era that a Democratic presidential nominee has won there.

However, in the region’s 39th congressional district, for example, 17 candidates are competing for the open GOP-held seat -- including six Democrats, despite party leaders’ efforts to winnow the field.

Republican candidates in 2018 might be reconsidering their strategy, particularly those running in conservative-leaning districts on pro-Trump agendas.

In Indiana, two GOP congressmen who essentially battled to out-Trump each other in a Senate bid, lost the party primary Tuesday to businessman Mike Braun, who ran as an outsider.

Also on Tuesday, three-term North Carolina Rep. Robert Pittenger lost his reelection bid to former pastor Mark Harris, becoming the first congressional incumbent to lose this year. And convict Larry Blankenship lost his GOP primary bid in West Virginia for a Senate seat.

The Empire State

Perhaps no House primary this year is as unusual at the 11th Congressional District race in New York, where former Republican Rep. Michael Grimm is trying to win back his seat.

Grimm resigned from Congress in 2014 after pleading guilty to felony tax evasion, then spending seven months in prison. His campaign could not be reached for comment.

Cook projects that Republicans have a better-than-even chance of keeping the seat.

Grimm is challenging GOP Rep. Dan Donovan, who replaced Grimm in a 2015 special election and ran unopposed in 2016.

The two candidates have wasted no time going negative -- each trying to claim the Trump mantle and making up derisive nicknames for each other, in the Staten Island-area district that supports the president. House Speaker Paul Ryan, R-Wis., and others are backing Donovan.

But Grimm, a former FBI agent, is remembered by voters for his efforts in the aftermath of Superstorm Sandy in 2012. Trump loyalist and Wall Streeter Anthony Scaramucci will reportedly headline a May 19 fundraiser for Grimm in his district.