From New England to the upper Midwest, four states are hosting primaries Tuesday.

The most interesting contests are in Wisconsin and Minnesota, which both hold primaries for Senate and for several competitive House seats. And in two safe Democratic districts — one in Minnesota and one in Connecticut — primaries will likely pick new members of Congress.

Wisconsin

Wisconsin Republicans will pick their nominee to take on Democratic Sen. Tammy Baldwin, one of 10 Senate Democrats running for re-election in states that President Donald Trump won in 2016. The contest between Marine veteran and businessman Kevin Nicholson and state Sen. Leah Vukmir has come down to the wire.

Both are backed by billionaires bankrolling super PACs. Vukmir has the state party’s endorsement, and the Wisconsin GOP’s turnout machine behind her. But Nicholson has benefitted from millions of dollars in outside spending to boost his campaign. Inside Elections with Nathan L. Gonzales rates the Wisconsin Senate race Leans Democratic.

Some Democrats see their best House pickup opportunity in Wisconsin in the 1st District, which opened after Speaker Paul D. Ryan decided to retire. Trump carried the district by 10 points in 2016, his smallest margin among all five GOP-held seats in the Badger State. Former Ryan aide Bryan Steil is expected to win the Republican nod, while ironworker Randy Bryce faces Janesville school board member Cathy Myers for the Democratic nomination.

A viral web video turned Bryce into a fundraising juggernaut last year, and he’s been dominating the airwaves. But it’s still a race, due in part to Myers’ local support, her own fundraising, and the unanswered question of whether she will garner support from female voters. Inside Elections rates the race Leans Republican.

ICYMI: Best of Speaker Paul D. Ryan — Congressional Hits and Misses

Minnesota

House primaries in Minnesota will set up two of the country’s most competitive races in open Democratic seats that Republicans are trying to flip in November.

The GOP primary in Minnesota’s 1st District, which covers the southern part of the state, is another test of whether Republicans can get a woman through a primary. State Sen. Carla Nelson is challenging four-time candidate Jim Hagedorn for the nomination. Hagedorn came within a point in 2016 of unseating Democratic-Farmer-Labor Rep. Tim Walz, who is running for governor. And while Hagedorn won the party endorsement earlier this year, Nelson elected to continue her campaign.

The primary has divided members of Congress, with female members, including New York Rep. Elise Stefanik, the National Republican Congressional Committee recruitment chairwoman, backing Nelson. GOP members of the Minnesota delegation such as Tom Emmer, the deputy NRCC chairman, and Erik Paulsen are sticking with Hagedorn. The winner is expected to face Iraq War veteran and former Pentagon official Dan Feehan, who has the DFL endorsement, in a Toss-up race this fall.

The DFL candidate in the 8th District in northeast Minnesota will go a long way toward determining the competitiveness of the general election. Races in the district the past two cycles have ranked among the most expensive. No one won enough support at the district DFL convention in April to win the party endorsement to replace DFL incumbent Rick Nolan — who is running for lieutenant governor — so five candidates are facing off in the primary Tuesday.

Former state Rep. Joe Radinovich, who managed Nolan’s 2016 campaign, is widely regarded as the front-runner. But former TV news anchor Michelle Lee, who spent 34 years on the air in the district, could pull off an upset if she runs up the score in Duluth, the district’s largest city, and capitalizes on her opposition to copper-nickel mining. State Rep. Jason Metsa is the most pro-mining candidate and has the backing of the United Steelworkers. But there may not be enough votes on the Iron Range to push him over.

Republicans have long united around former Duluth police officer and hockey player Pete Stauber. He’s already benefited from a rally with President Donald Trump, who carried the district by 16 points in 2016. Inside Elections rates the general election a Toss-up.

Democrats in Minnesota’s 5th District, which includes Minneapolis and the surrounding suburbs, will vote Tuesday to choose the likely successor to Rep. Keith Ellison, who’s running for state attorney general. State Rep. Ilhan Omar is the DFL-endorsed candidate, a firebrand progressive activist who would be the first Somali-American elected to Congress. She faces two main competitors: former state House Speaker Margaret Anderson Kelliher and state Sen. Patricia Torres Ray. The district is one of the most heavily Democratic in the country — Hillary Clinton carried it by 55 points in 2016.

At the Senate level, Republicans will face off to pick opponents to Democratic Sens. Amy Klobuchar and Tina Smith. The state GOP endorsed state Rep. Jim Newberger to run against Klobuchar and state Sen. Karin Housley to challenge Smith, who’s running to fill out the remainder of former DFL Sen. Al Franken’s term. But Smith faces a primary, too. Five other Democrats are trying to take her on, including Richard Painter, a former Republican and ethics lawyer to former President George W. Bush.

Connecticut 

Two women are facing off for the Democratic nomination in Connecticut’s 5th District, an open-seat race that Inside Elections rates Solid Democratic. That means whoever wins will likely be the next member of Congress. Current Rep. Elizabeth Esty isn’t running for re-election after facing criticism of her handling of a former top aide who was accused of sexually harassing and threatening a staffer. Mary Glassman, the 2006 lieutenant governor nominee, has the state party’s endorsement. But Jahana Hayes, the 2016 national teacher of the year, has the backing of organized labor groups such as the Service Employee International Union, the National Education Association and the AFL-CIO. Hayes is bidding to become the first African-American Democrat elected to Congress from Connecticut.

Jeff Cirillo contributed to this report.