Kyrsten Sinema, who rose from childhood homelessness to three terms in Congress, officially won Arizona's nationally watched U.S. Senate race on Monday, making her the state's first woman elected to the chamber.

Speaking to more than 100 supporters at the Omni Scottsdale Resort & Spa at Montelucia in Scottsdale, Sinema, 42, said the challenge for Arizonans is to heal and unite around love of country.

Republican rival Martha McSally conceded the race during a phone call to Sinema Monday evening after a week of painstaking ballot-counting that saw her narrow Election Day lead slip into a 38,000-vote advantage for Sinema.

In accepting victory, Sinema said she was grateful for McSally's service and said they both ran for the Senate because they both wanted what was best for the state. Beaming, Sinema said she was honored that voters chose her vision over one that stoked fear and anger.

"I am so honored that Arizonans chose our vision of a better Arizona, and now it's time to get to work," she said." Arizonans had a choice between two very different ways forward. One focused on fear and party politics, and one focused on Arizona and the issues that mattered to Arizona families.

"Arizonans rejected what has become far too common in our country: name calling, petty, personal attacks, doing and saying whatever it takes just to get elected. It's dangerous, and it lessens who we are as a country. Arizona proved that there is a better way forward."

Sinema preached a message of unity.

"We can work with people who are different than us. We can be friends with people who are different than us," she said. "We can love and care about people who are different than us. We can keep people who are different than us safe. We can be good people who care deeply about each other even when we disagree.

"It's dangerous and it lessens who we are as a country."

MORE:Read U.S. Sen.-elect Kyrsten Sinema's victory speech

Sinema also called for the state to come together in the style of the late U.S. Sen. John McCain, whose "country over party" message resonated with the dozens gathered to hear her speak.

Sinema pledged to "double down" on her style of politics in Washington, following in the style of McCain, saying his example will guide the way forward.

"He taught us to always assume the best in others, to seek compromise instead of sewing division, and to always put country ahead of party," she said.

No matter where she goes, she heard from thousands of voters that government is dysfunctional.

"Everyone recognizes that it's broken," she said. "And really, we all know the solution. We — we the citizens of this great country — we must fix it. We must be an active part of the solution. We must be willing to put down our sticks sharpened for battle. We must be willing to turn to our neighbors and pick them up instead."

A win for Arizona Democrats

Sinema's triumph is the first for Democrats in an Arizona U.S. Senate race in 30 years and brings down the GOP majority in the Senate to 51-47 seats. She will replace the retiring U.S. Sen. Jeff Flake, a Republican driven from re-election by pressure from President Donald Trump, who relentlessly attacked Flake for his criticism of his style of politics.

Sinema thanked supporters at the Scottsdale hotel against the backdrop of a jubilant crowd of Democrats, Republicans and independent voters. They whooped and hollered and held Sinema campaign signs aloft as the weight of the moment settled in.

MORE: Arizona Democrats turned the state more purple in 2018. Will it last?

They chanted "Kyrsten! Kyrsten!" as she took the stage.

Sinema will take office Jan. 3.

McSally wished Sinema the best in a video message that included her dog, Boomer.

"I wish her all success as she represents Arizona in the Senate," McSally said in the video posted on Twitter. She went on to thank her supporters for their effort on her behalf.

On the campaign trail

Throughout her hard-fought campaign, Sinema stayed focused on the people she sought to represent and positioned herself as a centrist Democrat who, on some issues, was more aligned with Republicans than her own party.

While McSally's campaign flew in high-profile Republican surrogates to appeal to every stripe of Republicans, Sinema played up her independence and commitment to "everyday Arizonans."

She pledged to not allow partisanship scuttle progress and appealed for a better health-care system for everyone while continually noting McSally stood with Republicans in their efforts to repeal the Affordable Care Act, which requires insurers to cover pre-existing health conditions.

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Sinema portrayed herself as a pragmatic lawmaker who is willing to break with party bosses and party lines to act in the best interests of the state, even when it angered the Democratic leadership.

And she survived tens of millions of dollars in negative political ads and attacks by McSally and Republican-aligned groups, principally allies of Senate Majority Leader Mitch McConnell, R-Kentucky.

After months of having the airwaves to herself, GOP ads dominated TV and radio throughout the general election. They slammed Sinema for wearing a pink tutu 15 years ago as she protested opposition to the invasion of Iraq.

They cast her as a "socialist." One mailer depicted a major explosion in downtown Phoenix if Sinema were elected.

The GOP attacks stood at odds with Sinema's record in the House, where she amassed one of the more moderate voting histories over the past six years.

Sinema's electoral victory rested largely on critical support from Maricopa and Pima counties, the state's two population centers.

She was leading in Maricopa County by 48,000 votes, or 3.7 percent. In Pima County, she led McSally by 54,000 votes, or 15 percentage points.

Sinema's nonpartisan message appealed to sizable numbers of independents and Republican women. While Sinema played down her Democratic affiliation, the party's faithful showed up in solid numbers and remained loyal to a candidate who kept her party's leaders at arm's length.

Sinema didn't vote for House Minority Leader Nancy Pelosi, D-California, in her three terms in that chamber and she has said she would not back Senate Minority Leader Chuck Schumer, D-New York, in the Senate.