Rep. Kyrsten Sinema (D-Ariz.) has won Arizona’s marquee Senate race, handing Democrats a major victory six full days after Election Day.

Sinema defeated Rep. Martha McSally Martha Elizabeth McSallyThe Hill's Campaign Report: Presidential polls tighten weeks out from Election Day Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' New ABC/WaPost poll finds Trump edging Biden in Arizona, Florida MORE (R-Ariz.) in one of the most closely watched Senate races this cycle. Sinema led by a margin of 38,197 votes, or about 1.7 percentage points, out of more than 2.1 million votes cast, when The Associated Press called the race on Monday.

The AP made the call after Sinema, who was first elected to Congress in 2012, increased her lead over McSally for the fifth straight day. Arizona still has about 200,000 ballots left to count, but McSally would have to win an improbable percentage of those remaining votes to overcome Sinema's edge.

"I just called Kyrsten Sinema and congratulated her on becoming Arizona's first female senator after a hard-fought battle," McSally said in a video posted to Twitter on Monday evening.

Congrats to @kyrstensinema. I wish her success. I’m grateful to all those who supported me in this journey. I’m inspired by Arizonans’ spirit and our state’s best days are ahead of us. pic.twitter.com/tw0uKgi3oO — McSally For Senate (@MarthaMcSally) November 12, 2018

Republicans feared McSally might not regain the lead she lost when new vote tallies were reported Thursday, though they held out hope that the ballots to be counted early this week would come from voters who dropped off their absentee ballots on Election Day.

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Those hopes appeared dashed Monday, when Maricopa County reported a tally of another 19,000 ballots.

Apart from Arizona, Nevada is the only other Senate seat that Democrats picked up this cycle. Rep. Jacky Rosen Jacklyn (Jacky) Sheryl RosenHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections Google, Apple, eBay to meet virtually with lawmakers for tech group's annual fly-in Senate Democrats demand answers on migrant child trafficking during pandemic MORE (D-Nev.) unseated Sen. Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE, who was the only GOP senator up for reelection in state Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE carried in 2016.

Democrats had not won a Senate seat in Arizona since 1988.

But President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE carried Arizona by less than 5 points in 2016, a closer margin than previous GOP presidential nominees.

The race to replace retiring GOP Sen. Jeff Flake Jeffrey (Jeff) Lane FlakeHow fast population growth made Arizona a swing state Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden MORE was one of the tightest contests in the country, and Trump loomed large. The president appeared at a rally with McSally in Mesa just two weeks before Election Day.

McSally overcame two more conservative challengers in the Republican primary, and she aligned herself closely with Trump. She focused much of her campaign messaging on immigration and border security in an effort to boost Republican turnout. McSally, a former fighter pilot, also hammered Sinema over her past anti-war protesting and progressive roots.

Sinema, who fashioned herself as a moderate, kept the focus on health care and protections for pre-existing conditions as a wedge issue with McSally, who voted for the GOP’s ObamaCare repeal bill.

With Arizona in the rearview mirror, a handful of other races around the country remain too close to call, including high-profile races in Florida and Georgia.

Recounts have been ordered in Florida’s hotly contested Senate and gubernatorial races.

And in Georgia, the governor’s race hasn’t been called, as Democrats hold out hope that remaining ballots could push the race into a runoff, though that remains an uphill battle.

Regardless of what happens in the remaining Senate races, Republicans have already secured a slim 51-47 seat majority.

In Florida, Gov. Rick Scott (R) holds a lead of roughly 12,500 votes over Sen. Bill Nelson Clarence (Bill) William NelsonDemocrats sound alarm on possible election chaos Trump, facing trouble in Florida, goes all in NASA names DC headquarters after agency's first Black female engineer Mary W. Jackson MORE (D), as a recount is underway. The two candidates are locked in a fierce litigation battle as election officials scramble to hit a Thursday deadline.

And in deep-red Mississippi, Sen. Cindy Hyde-Smith (R) faces former Agriculture Secretary Mike Espy (D) in the Nov. 27 runoff. Hyde-Smith has sparked backlash for joking about “public hangings.” Espy would be the first black U.S. senator from Mississippi since 1881.

— Reid Wilson contributed. Updated at 8:40 p.m.