Lanon Baccam will take on GOP Rep. Zach Nunn after primary win

Lanon Baccam won Tuesday's 3rd District Democratic primary and will challenge incumbent Republican Rep. Zach Nunn in November, per AP .

Why it matters: The southwest Iowa district represents a big chunk of the Des Moines metro, including Polk and Dallas Counties.

Driving the news: Baccam, an Army veteran and former USDA official, won the primary handily against Melissa Vine, a mental health therapist and nonprofit executive, according to preliminary results.

• Baccam had raised about twelve times more campaign funds than Vine.

The big picture: The District 3 election is expected to be the state's most competitive House race this year.

• Nunn, a former Iowa state senator and Air Force officer, narrowly ousted Democratic Rep. Cindy Axne just two years ago.

Between the lines: In the general election, Nunn has an incumbency advantage, Karen Kedrowski, director of the Carrie Chapman Catt Center for Women and Politics at Iowa State, tells Axios. He has the platform to tout his record on a range of issues, she said.

• In his first term, Nunn carved out a niche as a vocal moderate on key issues, Axios' Juliegrace Brufke writes.
• The freshman representative co-led a bipartisan resolution, for example, condemning the Hamas attack on Israel last fall.

Yes, but: First-term candidates like Nunn are easier to beat than longer-serving ones, Kedrowski said.

• Baccam, whose parents came to Iowa from Laos, has a compelling personal story that will resonate with many voters, she said.
• He also landed endorsements during the primary from some of the state's most prominent Democrats, including Iowa Auditor Rob Sand and former Iowa Gov. and current U.S. Agriculture Secretary Tom Vilsack.

The intrigue: Two other Iowa congressional races with Republican incumbents will also be in play come November, Kedrowski notes.

• 1st District Rep. Mariannette Miller-Meeks will again face Democrat Christina Bohannan, who she beat two years ago with just over 53% of the vote.
• 2nd District Rep. Ashley Hinson is being challenged by Democrat Sarah Corkery.

Zoom in: Other notable outcomes in local races include Polk County Supervisor Steve Van Oort being defeated in the Republican primary by Ankeny Mayor Mark Holm . Holm now faces Democrat Kim Hagemann in the general election.

• Jill Altringer beat Bob Start in the Republican primary to replace retiring Polk County Supervisor Bob Brownell, also a Republican. She'll challenge Democrat John Forbes in November.
• Rev. Rob Johnson won in the Democratic primary to fill the seat of retiring Rep. Ako Abdul-Samad, also a Democrat. He'll face Republican Danielle Duggan in November.

What we're watching: How much special interest groups get involved in the race.

• Nunn and Baccam reported total campaign cash as of mid-May of $1.9 million and $1.2 million respectively.