Incumbent Senator Mark Kelly has defeated Republican Blake Masters in the Arizona Senate race—a crucial win for Democrats who hope to maintain control of the upper chamber. After winning a special election last cycle to fill the remainder of late senator John McCain’s term, Kelly, a former astronaut and Naval aviator, will now serve his first full term. 

With Kelly’s win in Arizona, Democrats are just one seat away from keeping their majority in the Senate, with all eyes toward  Sens. Catherine Cortez Masto in Nevada and Raphael Warnock in Georgia.

Arizona was never seen as a sure bet; the state has become a highly competitive swing state in recent years amid an influx of new residents in the state’s growing metropolitan areas. Still, Democrats running statewide face significant hurdles, with Republicans making up the state’s largest voting bloc. 

Kelly came out on top thanks to a war chest in campaign funds; he raised more than $73 million, compared to just under $10 million for Masters, according to recent Federal Election Commission filings. Some Republican groups, including Minority Leader Mitch McConnell‘s Senate Leadership Fund, cut spending in the race to shift resources to contests deemed more gettable for the GOP.

At roughly this time last year, Arizona was seen as one of the GOP’s top pickup opportunities in the 50-50 Senate, given the political and economic headwinds for Democrats. But Masters, a Peter Thiel protégé with zero political experience, proved to be a poor general election candidate. After surviving a bitter primary contest—thanks to an endorsement from Donald Trump and $14.5 million in funding from Thiel—Masters spent much of the general election backtracking from his past hardline positions, including his billing as a “100% pro-life” candidate.

In contrast, Kelly championed abortion rights throughout the general, making a campaign promise to codify abortion protections established by Roe v. Wade, the ruling struck down by the Supreme Court earlier this year. (Arizona’s current abortion laws ban most procedures from taking place after 15 weeks of pregnancy—a standard that Masters said he would support nationwide—while a a more stringent ban is being litigated in the state.)

On immigration, one of the GOP’s top rallying points in Arizona, Kelly positioned himself to the right of his party’s leadership. During the race’s only debate, he called for the Biden administration to heighten border security by renovating border fences and recruiting additional Border Patrol agents to Arizona.