(CNN) Minnesota is home in 2018 to an open gubernatorial contest, two US Senate races and four highly competitive House matchups, making the North Star State the center of the midterm universe.

The four key House races, in particular, are likely to serve as a forecast for the future of both political parties.

Republicans are playing defense in two suburban/exurban Twin Cities districts -- one where President Donald Trump eked out a win and another where he lost to Hillary Clinton by nine points. For Democrats, the path to the House majority runs in large part through more affluent, educated turf such as Minnesota's 2nd and 3rd Districts, where Republican Reps. Jason Lewis and Erik Paulsen face tough re-election bids from well-financed challengers.

Democrats, meanwhile, are trying to hold onto two open seats in rural parts of the state that Trump carried by 15 and 16 points respectively.

Two of the few GOP pickup opportunities

In the 1st District, Democrat Dan Feehan is running against Republican Jim Hagedorn in a battle to replace outgoing Rep. Tim Walz, who is running for governor. Walz's presence at the top of the Democratic ticket could help Feehan, a US Army veteran and former acting assistant secretary of defense.

The 8th District, which is home to Duluth and the Iron Range, features a contest between Democrat Joe Radinovich, a former state lawmaker, and Republican Pete Stauber, a former professional hockey player and retired police officer. For Republicans, the 8th District represents the party's best opportunity to flip a seat currently held by Democrats in November.

Rep. Steve Stivers, the chairman of the National Republican Congressional Committee, has pointed to the House races in Minnesota as his bellwether contests this cycle.

"If we win both of our incumbent races and either of the challenger races, we will be in the majority," Stivers recently told reporters. "If we win one of the incumbent races and one of the challenger races, we're probably in the majority. If we lose both the incumbent races and win none of the challenger races, we are probably in the minority."

Democrats believe if they can come away with an even split in the four races then it bodes well for their prospects of taking back the House. Going three-and-one would signal a great night on November 6.

Those scenarios will be put to the test in 42 days.

For much of the year, these four Minnesota contests have been locked in the Toss-Up column. Entering the final six weeks of the campaign, the two Republican-held seats appear to have shifted slightly in favor of the Democrats.

A 2016 rematch, with a twist of controversy over political correctness added in

The race in Minnesota's 2nd District is a rematch of 2016, when Lewis defeated Democrat Angie Craig by about 6,000 votes with an independent candidate, Paula Overby, receiving more than 28,000 votes. This time around, Lewis and Craig will square off one-on-one in a year when the national environment and enthusiasm favors Democrats.

Trump carried the 2nd District by fewer than 5,000 votes while narrowly losing the state by a point to Clinton. But Democrats have had success in the 2nd District in previous campaigns. Barack Obama won it during both of his presidential bids. Gov. Mark Dayton and Sen. Amy Klobuchar, who is also on the ballot this year, have carried it during their statewide races.

While some of Lewis' controversial remarks as a talk radio host received attention in 2016, new comments have come to light that have resulted in fresh scrutiny. Among them: Lewis lamenting not being able to call women "sluts" anymore and claiming black and Hispanic communities are "addicted" to government welfare . Lewis is running a television ad where he admits not being "the most popular guy in Washington" and decries "politically-correct politicians" who "take my words out of context."

Craig, a former health care executive, raised $4.8 million for her first bid and another $2.3 million so far this time around. She nearly doubled Lewis in the second quarter and as of late July held a $1.7 million to $1.3 million lead in cash on hand.

The race in Minnesota's 2nd District moves from Toss-Up to Lean Democratic in our updated ratings. So does the neighboring 3rd District.

An unconventional campaign on land and water against a GOP veteran

Paulsen, a five-term congressman, has managed to win races when the political winds were against him. Paulsen carried the district in 2008 and 2012. So did Obama. Then, in 2016, he won by 14 points while Clinton took the district by nine points over Trump.

This year, Paulsen is running against Democrat Dean Phillips, CEO of Penny's Coffee and former co-owner of Talenti Gelato. Phillips is running an unconventional campaign, traversing the district in a revamped 1960s milk truck dubbed the "Government Repair Truck" and, when he's on water, a pontoon boat. Phillips' campaign recently released a parody video featuring Bigfoot trying to capture an elusive Paulsen, staking out a pharmaceutical company to finally capture a sighting of the congressman.

A recent New York Times Upshot / Siena College poll showed Phillips with a nine-point edge over Paulsen, 51% to 42%, despite roughly half of respondents saying they didn't know enough to have an opinion about the Democratic challenger. One explanation: 62% of voters in the district disapprove of the President's job performance while just 33% say they approve. It should be no surprise, then, that Paulsen's first TV ad highlighted the fact he broke with the President on environmental protections in the state. Paulsen holds a commanding cash-on-hand advantage, but that might not be enough in a district where the President is deeply unpopular.

In addition to the two Minnesota moves, we are shifting seven other races toward the Democrats and one in the direction of Republicans. As a reminder: Democrats need to gain 23 seats to win control of the House. CNN now rates 14 seats held or vacated by Republicans as Lean Democratic or better for Democrats. Of the 28 races rated Toss-Ups, the only two currently held by Democrats are the aforementioned contests in Minnesota.

To the rest of the races:

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CO-06: Five-term GOP Rep. Mike Coffman has frustrated Democrats with his ability to hold on in this diverse suburban Denver district that backed Obama twice and went for Clinton by nearly 10 points in 2016. Democrats this cycle recruited first-time candidate Jason Crow, a lawyer and former Army Ranger, to challenge Coffman, an Army and Marine Corps veteran. Crow's strategy is to negate Coffman's moderate personal brand by tying him to Trump as often as possible. Disapproval of the President's job performance in the district stands at 59% according to a Five-term GOP Rep. Mike Coffman has frustrated Democrats with his ability to hold on in this diverse suburban Denver district that backed Obama twice and went for Clinton by nearly 10 points in 2016. Democrats this cycle recruited first-time candidate Jason Crow, a lawyer and former Army Ranger, to challenge Coffman, an Army and Marine Corps veteran. Crow's strategy is to negate Coffman's moderate personal brand by tying him to Trump as often as possible. Disapproval of the President's job performance in the district stands at 59% according to a NYT/Siena poll . That survey shows Crow leading Coffman by 11 points -- 51% to 40% -- with more 6th District voters holding an unfavorable view of the GOP incumbent (41%) than having a favorable opinion of him (38%). Coffman acknowledged the President has been a drag on his candidacy.

"It's less about his policies than it is about his tone," Coffman recently told CNN's Dana Bash . "College-educated independent women just really are offended by his tone and his mannerisms in the office. So it's baked in now."

Race moves from Toss-Up to Lean Democratic

FL-27: Dueling internal polls show a competitive race between Democrat Donna Shalala and Republican Maria Elvira Salazar. When 15-term GOP Rep. Ileana Ros-Lehtinen announced her retirement from this Miami-based seat, it immediately shot up the Democratic target list. Ros-Lehtinen won the seat by 10 points in 2016 while Clinton carried it by 19 points, an increase from Obama's six-point margin four years earlier. Shalala, a former secretary of health and human services in the Clinton administration, scored a closer-than-expected primary win last month. Now party officials are sounding the alarm about her bid -- one critic telling Dueling internal polls show a competitive race between Democrat Donna Shalala and Republican Maria Elvira Salazar. When 15-term GOP Rep. Ileana Ros-Lehtinen announced her retirement from this Miami-based seat, it immediately shot up the Democratic target list. Ros-Lehtinen won the seat by 10 points in 2016 while Clinton carried it by 19 points, an increase from Obama's six-point margin four years earlier. Shalala, a former secretary of health and human services in the Clinton administration, scored a closer-than-expected primary win last month. Now party officials are sounding the alarm about her bid -- one critic telling Politico's Marc Caputo Shalala's campaign is in "sleep mode." Republicans, meanwhile, are high on Salazar, a well-known former Spanish-language television reporter. The environment favors Shalala, but "candidates matter" is a cliche for a reason. One external factor that might benefit Shalala is the gubernatorial campaign of Democrat Andrew Gillum, who saw strong support in Miami-Dade in the August primary.

Races moves from Lean Democratic to Toss-Up

GA-06: First-term GOP Rep. Karen Handel defeated Democrat Jon Ossoff by four points in a fiercely-contested and high-cost 2017 special election to fill the seat vacated by former Secretary of Health and Human Services Tom Price, who had held the seat since 2004. Former House Speaker Newt Gingrich represented the area for two decades. But Democrats believe the rapidly-changing demographics of this district, home to Atlanta's well-off northern suburbs, will make this race competitive in November. Trump carried the district by a single point, 48% to 47%, in 2016 -- a sharp decline from Republican Mitt Romney's 61% to 37% spread in 2012. The Democratic candidate in the race is gun control activist Lucy McBath, whose son was shot and killed in 2012 after a dispute over loud music. The high-profile race for Georgia governor between Republican Brian Kemp and Democrat Stacey Abrams, who could become the country's first black female governor, is likely to boost turnout for down-ballot races across the state.

Race moves from Likely Republican to Lean Republican

IL-06: Will GOP Rep. Peter Roskam, first elected amid the Democratic wave of 2006, be able to withstand the political currents of 2018? This suburban Chicago seat where a majority of residents hold a college degree is exactly the kind of district Democrats are eyeing to lift the party back to the majority in the House. Trump only received 42% of the vote here in 2016, losing the district by seven points to Clinton. That was a swing from 2012, when Romney carried the district 53% to 45%. A recent Will GOP Rep. Peter Roskam, first elected amid the Democratic wave of 2006, be able to withstand the political currents of 2018? This suburban Chicago seat where a majority of residents hold a college degree is exactly the kind of district Democrats are eyeing to lift the party back to the majority in the House. Trump only received 42% of the vote here in 2016, losing the district by seven points to Clinton. That was a swing from 2012, when Romney carried the district 53% to 45%. A recent NYT/Siena poll found 57% of voters in the district disapprove of the job Trump is doing as president. That survey also found Roskam and his Democratic challenger, Sean Casten, locked in a close race at 45% to 44%. Casten, a scientist and clean energy businessman, has drawn scrutiny for some controversial statements, including comparing the President to Osama bin Laden . He later said he regretted his comments. Casten has also sought to put Roskam on defense for not being a check on the President and for supporting Trump's agenda, especially the GOP tax plan, which the Democrat says could hurt taxpayers in the district because of the cap on state and local deductions.

Race moves from Lean Republican to Toss-Up

IA-01: Two-term GOP Rep. Rod Blum won re-election by eight points in 2016, buoyed by Trump's success in the 1st District. The President carried the 1st by a 48% to 45% margin, a significant shift from four years earlier when Obama trounced Romney 56% to 42% in the northeast Iowa district. Of the 20 counties in the 1st District, 15 swung from Obama to Trump. The President's standing in the district is on shaky ground, with 55% of voters saying they disapprove of his job performance according to a Two-term GOP Rep. Rod Blum won re-election by eight points in 2016, buoyed by Trump's success in the 1st District. The President carried the 1st by a 48% to 45% margin, a significant shift from four years earlier when Obama trounced Romney 56% to 42% in the northeast Iowa district. Of the 20 counties in the 1st District, 15 swung from Obama to Trump. The President's standing in the district is on shaky ground, with 55% of voters saying they disapprove of his job performance according to a NYT Upshot/Siena College poll . Blum's challenger this year is 29-year-old Democratic state Rep. Abby Finkenauer, who has emphasized her working-class roots on the trail and in TV ads. The same NYT/Siena poll showed Finkenauer with a 52% to 37% advantage against Blum. The GOP incumbent is also facing a House Ethics investigation relating to a business he formed while in office that he did not disclose. Just 35% of voters in the district view Blum favorably compared with 53% who have an unfavorable view of the congressman. No outside groups are lining up to give Blum a boost on TV, according to Kantar Media/CMAG data, while Finkenauer is getting some help from the DCCC and House Majority PAC.

Races moves from Toss-Up to Lean Democratic

MO-02: Stivers, the NRCC chairman, says GOP Rep. Ann Wagner told him not to spend resources on her re-election bid, signaling a level of confidence in her campaign. It also doesn't hurt the three-term incumbent was sitting on nearly $3 million in the bank as of mid-July compared with $454,000 for her Democratic challenger, attorney Cort VanOstran. The 2nd District includes upscale suburbs of St. Louis where nearly half of residents 25 years and older have at least a Bachelor's degree. Trump's 52% vote share in the district was his lowest of the six GOP-held seats in the Show Me State, down from Romney's 57% mark in 2012.

Race moves from Solid Republican to Likely Republican

NY-27: GOP Rep. Chris Collins' surprise decision to actively campaign for re-election despite being indicted on insider trading charges in August blindsided Republicans. The move could give a boost to Democrats hoping to flip the most GOP-leaning district in the Empire State. Collins, who faces charges of securities fraud, wire fraud and false statements, previously said he would suspend his re-election campaign. GOP officials believed they had a way to replace Collins on the ballot. The legal battle will hang over the contest as Collins seeks to fend off a challenge from Democrat Nate McMurray, the Grand Island town supervisor. Collins has $1.3 million in reserve for the campaign compared with about $81,000 for his opponent. McMurray says he's seen an uptick in fundraising since Collins was charged last month, a trend that could continue with Collins remaining in the race.

Race moves from Solid Republican to Likely Republican

NC-02: GOP Rep. George Holding's own campaign has been sounding the alarm about the incumbent's re-election prospects, sending a fundraising email to supporters last month sharing internal poll numbers showing him trailing his Democratic challenger, Linda Coleman, a former state lawmaker who has run two unsuccessful campaigns for lieutenant governor in the Tar Heel State. Coleman's campaign followed suit, releasing a poll showing the race a dead heat. Holding received 57% of the vote in each of his previous three races in this Raleigh-area district and has raised six times more money than Coleman, allowing him to run TV ads during the summer. The DCCC recently added Coleman to its "Red to Blue" candidate list, which should bolster her fundraising and organization in the final weeks of the campaign.

Race moves from Likely Republican to Lean Republican