"But the election is over, and we need to start the healing," she went on. "We need to turn down the rhetoric and start listening once again. We have to start listening, folks, because we are all Americans, and there is far more that unites us than divides us."

Iowa voted to send Trump back to the Oval Office Tuesday, handing the incumbent six electoral college votes in his bid for a second term.

Greenfield entered the race with a limited political profile after she was forced to cut short her first bid for office — a 2018 House race — after her campaign manager forged signatures to get on the ballot without Greenfield’s knowledge. But Greenfield quickly earned endorsements from officials in Washington and Iowa to become the party favorite in the race.

"I did congratulate her on a hard-fought campaign," Ernst said Wednesday. "I respect anyone who was willing to throw their hat in the ring for public service, and I thank Ms. Greenfield for doing that."

Greenfield navigated a competitive Democratic primary with a boost from outside groups, and the race between her and Ernst evolved into a dead heat through the summer and fall. Many expected the race to end up closer than it did, with Democrats and others viewing the seat as their best bet to flip blue and help hand the party the majority in the upper chamber.

"Folks, it’s been a long night and unfortunately we came up short," Greenfield wrote in a tweet Wednesday. "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," she went on. "And that fight doesn’t stop tonight."

Ernst won her first race in part with a famous ad promising to make Washington “squeal.” Six years later, Democrats tried to tie her to President Donald Trump and Washington in an effort to turn her out of office. Ernst also faced a steady stream of spending against her, with most of the Democratic ads either linking her to the president, highlighting her votes against the Affordable Care Act or accusing her of having lost her outsider edge in Washington.

The two candidates also competed for rural voters, with both emphasizing their upbringing on family farms. For Ernst, it was an effort to drive up margins to offset Democratic gains in the suburbs, while Greenfield was trying to limit GOP gains in rural territory. Greenfield focused heavily on her background, including the death of her first husband, a union electrician, and her reliance on Social Security and union benefits as a single mother at the time.

Republicans spent hefty sums on TV ads tearing down that image, criticizing Greenfield’s role as a real estate developer and arguing she harmed local small businesses.

Ernst, like other Republicans, struggled to raise money to compete with Greenfield, who became one of her party’s most successful small-dollar fundraisers despite starting the race with little infrastructure. Greenfield raised $47.5 million through October, compared with $24.1 million for Ernst.

Eleanor Mueller contributed to this report.