Democrat Greg Stanton has defeated Republican Steve Ferrara in the battle for Arizona's 9th Congressional District, according to the Associated Press.
With over 72,000 votes counted, Stanton had 59.6 percent of the vote; Ferrara had 40.4 percent.
Stanton, the former mayor of Phoenix, won the seat held by Democrat Kyrsten Sinema, who gave up the seat in order to run for the U.S. Senate.
The 48-year-old Stanton served as mayor of Phoenix from 2012 until May of this year, when he resigned in order to run for Sinema's seat.
Ferrara served in the U.S. Navy for 25 years. He has worked as a physician and a clinical professor of radiology.
The win is a hold for Democrats, who are looking to claim a majority in the House of Representatives for the first time since 2010.