Updated

Incumbent U.S. Sen. Joni Ernst, R-Iowa, has staved off Democratic challenger Theresa Greenfield in one of the most contested races of the 2020 campaign, Fox News projects.

Ernst won more than 861,000 votes, or about 51.8%, with 99% of the results counted. Greenfield received more than 751,000 votes.

"It has been such a great honor to serve as your United States senator for the past six years, and I look forward to continuing that fight over the next six years," Ernst said during her victory speech.

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The Iowa seat is critical for Republicans in their quest to retain control of the Senate, which signs off on both cabinet nominations and judgeships. More than $200 million had poured into the race, much of which had come from New York and California, with the hopes of turning the state blue. 

Sen. Joni Ernst

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Ernst, who visited all 99 counties in the state, was confident her persistence would secure her another term, telling Fox News those visits would put her "over that finish line.” She told Fox News that Greenfield had traveled to less than half. 

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The race between Ernst and Greenfield, a real estate developer, was tight throughout with the Republican senator pulling ahead in the polls in the week leading up to the election. Polls compiled by RealClear Politics showed Greenfield with a 5-point lead at the beginning of October.