Incumbent Democrat Sen. Mark Kelly has defeated his Republican challenger, Blake Masters, in Arizona, boosting Democratic hopes of holding onto the Senate.

With 83% of votes counted, the Associated Press called the race Friday evening for Kelly — a Navy combat veteran, retired NASA astronaut and the husband of former Rep. Gabby Giffords, D-Ariz. He leads Masters, a 36-year-old “anti-progressive” venture capitalist, by an insurmountable 52% to 46% margin.