Iowa's 1st and 3rd District races are now toss-ups

• Control will likely come down to the winners of a handful of competitive districts, NBC News reports.

3rd District

Republican incumbent Rep. Zach Nunn is being challenged by Democrat Lanon Baccam, an Army veteran and former USDA official.

Flashback: Nunn narrowly won the district when he ousted Democratic Rep. Cindy Axne by just over 2,000 votes two years ago.

State of play: The district is dominated by Des Moines and home to a growing number of voters who have moved away from the GOP.

• Baccam's ads reminding voters of Nunn's previous support for an abortion ban without exceptions has been damaging, per Cook.

1st District

Republican incumbent Rep. Marianette Miller-Meeks again faces Democratic former state Rep. Christina Bohannan, whom she beat two years ago with just over 53% of the vote.

Zoom in: Miller-Meeks, who previously served in the Iowa Senate, ran for the U.S. House three times before winning in 2020 by a margin of just six votes.

• Voters in the southeast Iowa district have never really warmed to Miller-Meeks, while Bohannan has been running an effective campaign, according to Cook.

Follow the money: Campaigns and political action groups in the 3rd District have spent nearly $20 million in this election cycle, with spending about even between both parties.

• Spending in the 1st District has surpassed $17 million, of which Democrats account for nearly $10.4 million, per the tracking firm AdImpact.

The big picture: Iowa Democrats are increasingly optimistic following Vice President Kamala Harris' nomination, and they're counting on public backlash against the state's new six-week abortion ban to help them win.

• If that optimism brings more people to the polls, it could influence outcomes for down-ballot races and block a repeat of Iowa's red wave in 2022, political scientists tell Axios.