While the Republican primary was at-times ugly, Sinema practically cruised to victory and now the two fellow congresswomen are headed into what’s expected to be one of the season's most competitive races.
There has been no widespread, airworthy polling done in the race yet, but it’s been ruled as a “toss up” by political analysis site Larry Sabato’s Crystal Ball.
Sinema said that some of what’s driving that possible flip from red to blue could be the current state of politics in D.C.
"I think is what’s driving Arizona voters this year, that they are facing a very chaotic and dysfunctional Washington, D.C., that doesn’t serve them and they’re looking for elected leaders who will just roll up their sleeves and get the job done," Sinema told ABC News on Monday, before suspending the campaign amid the McCain memorials.
Drew Anderson, a spokesperson for the Arizona Democratic Party, said that the shift to the right that McSally decided to make during the primary in order to win support from the state’s conservative base will help in the fight for the state’s moderates and independents.
“She has already casted herself as a Trump loyalist, without a doubt she would back him 100 percent of the time,” Anderson said of McSally.
By contrast, Anderson said that Sinema is a moderate Democrat, which he said could help with suburban voters.
“A kind of candidate like Kyrsten is the kind of politician that moderate suburban voters gravitate to,” Anderson said.
Moderate might be a winning label in Arizona given a report on voter demographics put together by the nonpartisan Citizens Clean Election Commission and Arizona State University, showing nearly as many independents in the state as Republicans in 2016.
Gail Covington McBride, a former schools superintendent and Democrat who lives in the southern Arizona town of Bisbee, made a similar point to ABC News, saying that Sinema has wide appeal.
“She’s highly educated. She’s a smart person and she is appealing to the independents, the people that could be swayed that might vote for McSally or not. She’s a strong woman. She’s a strong candidate and we have a chance of getting that seat,” Covington McBride said.
Even before the primary was over, McSally took aim at Sinema, launching an ad comparing their whereabouts on Sept. 11, with McSally beside a fighter jet and Sinema protesting in a pink tutu.
But the ad, one of the first noteworthy shots across the aisle by McSally at the end of a contentious primary, didn't fazed Sinema, she claimed. Instead, she says she remains focused on her home state.
"I leave all of that kind of stuff to the pundits and what I do, as everyone in Arizona knows about me, is just put my head down and get the work done and right now I am 100 percent focused on listening to Arizonans and doing my best to earn their vote," Sinema said.
One vote that she earned, albeit a bit begrudgingly, in the primary was that of Mary Eden, a native Arizonan who lives in the state again after a lengthy stint in California.
“It’s not with a lot of joy,” Eden said when walking into a Phoenix polling location to hand-deliver her mail-in ballot.
“I just really want to be clear about what she wants and what she wants for the Democratic Party,” Eden said.
In her call with ABC News, Sinema said that she’s been “hearing the same concerns over and over again” from Arizonans, including affordable health care, veteran care and jobs.
“Those are not issues that are Republican or Democrat. Those are just issues that Arizonans have every day to try and take care of their families and get that shot at the American dream,” she said.
To that point, Covington McBride said that Sinema’s commitment to affordable health care is a big part of the reason why she’s supporting her.
“Sinema supports health care and I support Sinema,” Covington McBride said.
For his part, Anderson is optimistic about the congresswoman's prospects in November given the state's current political climate.
“I think what you’re going to see is that a hefty amount of those voters will either not show up or for the first time in their life vote for someone other than a Republican candidate," he said.
Attack ads starting early
Though she has served in Congress since 2013 and was a member of Arizona's state legislature for eight years prior, Sinema largely flew under-the-radar this summer while the state's colorful Republican Senate primary attracted national eyeballs.
It was only in recent weeks, as the establishment-backed McSally began to pull away from rivals Kelli Ward and Joe Arpaio, did attention turn to Sinema.
The pink tutu doesn't appear until midway through the commercial, but it remains the advertisement's enduring image. The takeaway, McSally says in a television spot released this past week that attacked her now opponent, is that Sinema doesn't respect the military and isn't the leader Arizona needs in a "dangerous" world. The Republican further highlights her own Air Force experience as a fighter pilot and deployments to the Middle East.
After being raised a Mormon and graduating from Brigham Young University, Sinema left the church, earned a law degree and Ph.D., worked as a social worker, volunteered for Ralph Nader's presidential campaign, and, as the McSally campaign is quick to note, was outspoken in her opposition to the Iraq War.
But in an increasingly polarized political landscape, the third-term congresswoman has reshaped herself as a pragmatist and and one well-positioned to cater to an Arizona constituency accustomed to senatorial independence. Both Flake and McCain roiled the Trump White House over the past year and a half as they spoke out against the president and, as was the case when McCain cast the deciding vote against health care reform, sunk key items on the administration's agenda.
"People who are just very practical and common sense and focused on solving the problems that everyday Arizonans face," she added, a description that one could imaging Flake and McCain using to describe their work since Trump's election.
It's debatable, however, whether the state's electorate still has an appetite for a senator so detached from the White House. Asked Tuesday whether he could have won the Republican primary, much less re-election in November, Flake was blunt.
"Not a chance. Not a chance today," he told reporters Tuesday, hours before the state's primary was called. The senator noted that he was rooting for McSally, but acknowledged his party had to "appeal to a broader electorate."
"I think long-term, if we don't ... quit trying to drill down harder on the base and just give in to the politics of anger and resentment, we're going to lose big time," Flake said
In seeking to flip the Senate seat and bring the party one step closer to possibly winning a Senate majority in November, Arizona Democrats are focused on Sinema's potential to win over independents and moderate voters, particularly as the state's Republican Party moves to the right.
"[Republicans] are alienating these moderate voters when it comes to voting, whether it's on issues like education or health care, they will side with the Democratic Party because it's a more reasonable adult-in-the-room approach to governing," said Anderson.
Anderson alluded to McSally's seeming embrace of the president over the course of the Republican primary. In her quest for her party's nomination, McSally faced two opponents in Arpaio and Ward who backed Trump with fervor ranging back to before his election. It remains to be seen whether McSally might return to her moderate roots -- she is a member of the centrist Republican Main Street Partnership -- in the general campaign.
"She has already cast herself as a Trump loyalist. ... She has touted that she has a 97 percent voting record with him," Anderson said, adding. "Any sort of pivot that she would attempt would fall flat."
According to 538's congressional tracker, McSally has voted with Trump 97.8 percent of the time. That said, Sinema has the highest percentage of any Democrat in Arizona, as the same tracker reports that she has voted with Trump 60.9 percent of the time, including on some legislation - like the effort to roll back parts of the banking bill Dodd-Frank - which earned liberal ire.
By contrast, Arizona's other Democratic representatives voted with Trump less frequently: Rep. Tom O'Halleran voted with Trump 54.4 percent of the time, Rep. Ruben Gallego voted with him 15.9 percent, and Rep. Raul Grijavla voted with Trump only 8.9 percent of the time.
McSally faces a tough road ahead, despite raising $7.6 million in her contentious primary, according to Open Secrets.
Turning to November, she could be at a slight disadvantage against Sinema, the first openly bisexual member of Congress, who after holding a commanding lead over Deedra Abboud throughout her primary race, amassed a steep fundraising stockpile.
The Democratic nominee raised over $10.5 million as of Aug. 8, according to Open Secrets, in a clear signal of her attention: the general election.
Sinema’s focus on November is also evidenced by her string of ads, in which, she highlights support for veterans and law enforcement, and casts herself as more of an independent and a mediator.
In one ad, Sinema boasts a “fiercely independent record” and in another, she brands herself as someone who can “bring people together.”
Although Sinema easily captured her party’s backing for November, McSally fought a multi-pronged war for the Republican nomination. But now, she’s contending with possibly a more arduous uphill battle.
No matter the outcome, Arizona is set to send the first woman to the Senate in the state’s history. And that's appealing to some of Sinema's supporters.
"It would be great [if she won] -- the first woman senator for Arizona,” Eden said.
ABC News' Mariam Khan contributed to this report.