OMAHA, Neb. (AP) — The fate of Nebraska's "blue dot" — a small, but significant factor in presidential politics — will take center stage Tuesday as Democratic voters select a congressional nominee in the state's high-profile 2nd District.

The Omaha-area district, where Republican U.S. Rep. Don Bacon is retiring, is one of the Democratic Party's biggest targets this midterm season. It's also a national focus every four years in presidential contests because Nebraska is one of just two states that splits its electoral votes. The 2nd District has gone to Democratic presidential candidates three out of five times since 2008 — a "blue dot" in an otherwise sea of red.

Three Democrats are seen as the top contenders in Tuesday's primary: state Sen. John Cavanaugh, political activist Denise Powell and district court clerk Crystal Rhoades. Republican Brinker Harding, an Omaha City Council member endorsed by President Donald Trump, is running unopposed on the GOP side.

Cavanaugh, more than anyone else on Tuesday's ballot, has been under attack from both parties.

Some Democratic opponents argue that a primary victory for Cavanaugh would jeopardize the district's "blue dot" status because he'd be leaving his valuable state legislative seat, making it easier for Republicans in the Nebraska Legislature to change the law that allows the state to split its electoral votes.

The issue has defined the primary contest perhaps more than any other.

Opponents say the 'blue dot' is in danger

The Democratic argument against Cavanaugh has little to do with his politics or policies.

His opponents and groups backing them have flooded mailboxes, airwaves and social media warning that if he wins the congressional primary, Nebraska's Republican governor would appoint a conservative Republican to replace him in the Legislature.

That move, they say, could give state Republicans enough votes to enact a conservative wish list that includes stricter limitations on abortion and transgender rights.

It could also empower Republicans to enact midcycle redistricting or change the state's unusual system of splitting presidential electoral votes, some Democrats argue. Republicans failed in 2024 to pass a bill that would have made Nebraska the 49th state to award its Electoral College votes on a winner-take-all basis.

"Our Blue Dot. We fought hard for it. But if John Cavanaugh goes to Congress, it could all fall down," cautions one TV ad by the super PAC New Democrat Majority.

EMILY's List, a national group that supports women running for office, has put its reach and money behind Powell, calling Cavanaugh's candidacy "a gift to MAGA Republicans."

On Tuesday, Democrat Tony Vargas was out with his wife holding a large campaign sign and encouraging Omaha voters to support him in the county treasurer race. He also was supporting Powell in the congressional race, saying preserving the blue dot is important but not the only reason people might vote for Powell.

"I'm not voting for somebody for the blue dot loss. I'm voting for someone who I think is going to be the best leader in Congress," Vargas said.

Republican groups also target Cavanaugh

Republican groups have sent out mailers and social media posts claiming Cavanaugh "is in agreement with President Donald Trump" and showing a photo of Cavanaugh overlaid on a photo of the president, making it appear as if the two are standing together.

"Clearly, the Republicans know that I'm the strongest general election candidate," Cavanaugh said. "And so they're trying to hurt me."

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The attacks on Cavanaugh show Democrats and Republicans believe he has the best chance of winning the general election, said Paul Landow, a former Nebraska Democratic Party executive director.

He called the "blue dot" attacks disingenuous, noting Republicans already have a filibuster-proof majority in the Legislature but have still failed to pass key elements of their agenda because it is unpopular even among GOP lawmakers. The argument that a Cavanaugh win could weaken the state's "blue dot" also assumes Democrats won't pick up additional legislative seats this year, he said.

"There's so many things that have to fall into place for this alleged danger to the 'blue dot,'" Landow said. "It's just wild speculation."

The Democratic primary grows contentious

While all the Democratic contenders cite affordability and opposition to Trump administration policies — from immigration and healthcare to military actions — the top three contenders began attacking one another more aggressively in the days leading up to the primary.

Candidates and allied groups have spent more than $2.6 million on TV and digital advertising since Jan. 1, according to the advertising tracking company AdImpact. Nearly all of that has been by or on behalf of Cavanaugh and Powell.

Cavanaugh has spent about $375,000. Powell's campaign has spent almost as much — $345,000 — but with the help of groups backing her, campaign advertising has been overwhelmingly pro-Powell.

Powell co-founded Women Who Run Nebraska, a political action committee that supports progressive female candidates, and she has a decade of Democratic political activism. She's never held office but said her deep connections have helped her with independents and third-party voters who make up nearly 30% of the district's electorate.

"My name recognition has increased dramatically," Powell said, adding that "people are really connecting with my message."

Rhoades carries her own name recognition after 20 years in public service and running a slew of successful local Democratic elections — including that of Omaha Mayor John Ewing, who unseated a longtime Republican last year. Rhoades has raised a fraction of what Cavanaugh and Powell have amassed, but said she's intentionally eschewing campaign ads and instead blanketing the city with door-knocking and personal contact with voters.

Both Powell and Rhoades have leaned heavily into the concern that Democrats' influence in the district will erode if Cavanaugh is elected to Congress.

The winner of Tuesday's primary will head to a highly competitive general election. Trump won the district in 2016, and the retiring Bacon, who has clashed with Trump, has held the House seat for five terms.

Other Tuesday contests

Also on Tuesday's ballot is the race for U.S. Senate, where Republican incumbent Pete Ricketts is seeking a full term, following his 2023 appointment and 2024 special election victory to replace Republican Ben Sasse.

Ricketts faces four Republican primary challengers, but he's already looking ahead to an expected general election contest against independent candidate Dan Osborn, an industrial mechanic and military veteran who came within 7 points of defeating Republican U.S. Sen. Deb Fischer in her 2024 reelection bid. Running in the Democratic primary are William Forbes and Cindy Burbank.

In the race for governor, incumbent Republican Gov. Jim Pillen faces five primary challengers, while former state Sen. Lynne Walz and frequent candidate Larry Marvin compete for the Democratic nomination. Marvin previously ran for U.S. Senate four times since 2012.

Peoples reported from New York. Associated Press writer Josh Funk in Omaha, Nebraska, contributed to this report.