Mark Kelly, right, Arizona Democratic candidate for U.S. Senate, waves to supporters along with his wife Gabrielle Giffords, second from right, and daughters, Claire Kelly, left, and Claudia Kelly, second from left, during an election night event Tuesday, Nov. 3, 2020 in Tucson, Ariz. (AP Photo/Ross D. Franklin) Mark Kelly, Gabrielle Giffords, Claire Kelly, Claudia Kelly
Mark Kelly, right, Arizona Democratic candidate for U.S. Senate, waves to supporters along with his wife Gabrielle Giffords, second from right, and daughters, Claire Kelly, left, and Claudia Kelly, second from left, during an election night event Tuesday, Nov. 3, 2020 in Tucson, Ariz. (AP Photo/Ross D. Franklin)

“The work starts now.”

Democrat Mark Kelly won the Arizona Senate seat once held by late Sen. John McCain, riding Arizona’s changing electorate to flip a Republican Senate seat in a state long dominated by the GOP.

Arizona will send two Democrats to the Senate for the first time in nearly 70 years when Kelly joins Kyrsten Sinema in Washington.

Kelly, a former astronaut, defeated Republican Martha McSally, who was appointed to the seat by GOP Gov. Doug Ducey after McCain’s death in 2018. Since Kelly is stepping in to fill an appointed position, he can be seated as soon as Arizona’s elections are certified later this month.

Positioned as an independent-thinker, Kelly will have to live up to his claims of bipartisan leadership. Democrats are unlikely to secure a majority in the Senate, despite close races in states like North Carolina.

In his first run for political office, Kelly positioned himself as a pragmatic centrist with no patience for Washington partisanship. When the coronavirus pandemic struck, he retreated to mostly online outreach, minimizing face-to-face campaigning while blasting McSally and President Donald Trump for allowing the pandemic to get out of control.

“The work starts now. And we desperately need Washington to work for Arizona,” Kelly told a small group of family and reporters gathered for his victory speech in Tucson. “My top priority is making sure we have a plan to slow the spread of this virus, and then getting Arizona the resources our state needs right now.”

Kelly’s victory delighted Democrats and was sure to bring a reckoning for Republicans who have enjoyed decades of dominance in Arizona politics.

“Now people recognize that Arizona is in play, will always be in play,” said U.S. Rep. Ruben Gallego, a Phoenix Democrat who comfortably won reelection.

In turning toward friendly territory for Democrats, Arizona is following a path blazed by its neighbors Colorado, New Mexico, and Nevada. It’s also the Democrats’ brightest light among the Sun Belt states they tried to flip from the GOP this year.

A decade of work organizing Latinos to vote helped Arizona Democrats outperform other states where Democrats came up short, Gallego said.

Arizona Democrats benefited from the state’s changing demographics — with more young people and Latinos registering, an influx of new residents from more liberal states like California and growing support among some suburban women for Democratic candidates.