Democrat state Sen. Sarah McBride is projected to become the first openly transgender person to serve in Congress, ABC News projects.
She ran against Republican businessman John Whalen III.
With significant advantages in party registration numbers and campaign contributions, McBride was the favorite in the House race.
McBride has established a national profile as an LGBTQ activist and raised more than $3.5 million in campaign contributions from around the country. She achieved national recognition at the 2016 Democratic National Convention as the first openly transgender person to address a major party convention in the United States.
After scoring an easy Democrat primary win in September, McBride said she was not running for Congress to make history, but instead "to make historic progress for Delawareans."
As a state senator, McBride has earned a reputation for working on healthcare issues, including successfully sponsoring legislation to create a statewide paid family and medical leave insurance program. She also sponsored legislation regarding Medicaid reimbursement rates for home healthcare services and expanded access to dental care for low-income Delawareans. Another bill she sponsored imposed a 3.58% tax on the net revenue of Delaware hospitals to leverage additional federal Medicaid funds. All of those bills became law.
Democrats have held Delaware's U.S. House seat since 2011. This year's race opened up last year after Rep. Lisa Blunt Rochester said she would finish this term and run for the U.S. Senate seat being vacated by fellow Democrat Tom Carper.