Sen. Joni Ernst of Iowa, a close ally of President Donald Trump, has held on to her Senate seat, NBC News projects.
The contest was an expensive one, an indicator of its importance to Republicans and Democrats alike. The Democratic challenger, Theresa Greenfield, raised slightly more than $47 million and spent over $43 million. Ernst, meanwhile, raised $23.5 million and spent more $21 million.
With 91 percent of the vote counted, Ernst was leading by 51.7 percent to 45.3 percent.
Ernst thanked her supporters and declared victory on Twitter.
The bellwether race was considered an important indicator of Trump's electoral prospects, as well as the balance of power in the Senate. NBC News projects that Trump won the state Tuesday.
Ernst's campaign said Greenfield had called Ernst earlier in the evening to concede.
"Folks, it's been a long night and unfortunately we came up short," Greenfield said on Twitter. "I couldn't be more proud of the work we all put in. This race was never about me — it's about creating a future that works for all Iowans. And that fight doesn't stop tonight."
Ernst appeared to have a slight edge in late polling before the election, but Democrats outpaced Republicans in mail-in and early in-person ballots returned, according to NBC News' Decision Desk/TargetSmart.
Having grown up on an Iowa pig farm, Ernst promised Iowans in 2014 that if they sent her to the Senate, she'd hold Washington accountable and "make 'em squeal."
But one possible reason for the closeness of the race was that she didn't make Trump "squeal" very often, despite an election cycle in which it seemed that the top of the ticket could define the results for everyone else.
"She told us she was going to be independent, different and 'make 'em squeal,'" Greenfield said in a debate last month. "But unfortunately, she's become part of the problem."
Ernst tied herself very closely to the president. She defended her support of Trump, including his most recent Supreme Court nomination, but she said she was "running on my own issues."
Although Ernst admitted that hitching her cart to an unpopular president was a gamble, she told reporters that she thought Trump would carry Iowa. Late in the race, she attempted to highlight her independence and bipartisanship bona fides.
"I've ranked as one of the most bipartisan senators in the United States Senate from any state of either party in the last 25 years," she told reporters last month. "That speaks to the fact I'm working across the aisle, I'm working to get things done for Iowans, and I don't care what party so long as I'm working for Iowa."
Ernst's Iowa credentials were called into question last month when a debate moderator asked about the price of soybeans — a major crop in the state.
"It depends on what the inputs are, but probably about $5.50," she said.
"Well, you're a couple dollars off, because it's $10.05," the moderator responded.
Greenfield's campaign immediately jumped on the gaffe. "A Senator from Iowa should know the price of soybeans," it tweeted.
Greenfield also grew up on a hog farm, but she later developed a real estate business in central Iowa. Running as a moderate Democrat, she focused her campaign on health care access, the pandemic response, infrastructure funding, education support and farming.
When asked for the price of corn at the same debate, she had the correct answer.