Arizona's Senate race is pitting a hard-line conservative and a progressive against each other, shaping the race up as one of the biggest rebranding battles of the 2024 election cycle, political insiders told ABC News.

Kari Lake, the failed 2022 GOP gubernatorial nominee who became a right-wing rockstar over her unfounded election fraud claims, and Democratic Rep. Ruben Gallego, the five-termer with a sharp liberal bent and even sharper barbs for those he disagreed with, are running for an open Senate seat in a state wary of elevating firebreathers of any ilk to statewide office.

Now, both are trying to smooth their hard edges to win over the middle-of-the-road voters who will likely decide the victor in the Arizona Senate race -- and, possibly, control of the entire chamber.

"What's interesting is that Kari Lake, running as a true MAGA acolyte and election denier now is trying to rebrand, whereas Ruben Gallego, an incredibly liberal congressman, I mean, Ruben Gallego now to Ruben Gallego two years ago, you wouldn't almost recognize him," said Arizona-based pollster Mike Noble.

Lake has already drawn national headlines for her rebrand. She's shifted from calling abortion the "ultimate sin" and supporting Arizona's Civil War-era restrictions on it to advocating for leaving decisions on the procedure to the states and advocating for compassion around the issue. Since launching her campaign, she promised to work with any lawmaker in the Senate after savaging establishment Republicans like GOP Leader Mitch McConnell, R-Ky., and saying she'd drive a stake through the heart of the "McCain machine," referencing the late Sen. John McCain, R.

And while she still talks of a stolen election in 2020 and 2022, it is less of a centerpiece of her stump speech, even as she claims "nothing's changed in me."

Gallego, meanwhile, quietly let his membership in the Congressional Progressive Caucus lapse, has advocated for stricter border reforms than he has in the past, dialed down harsh -- and at times profane -- past rhetoric toward critics, and is focusing more on his personal story as a Latino Iraq War veteran raised by a single mother, as seen in his first campaign ad.

The jolts to the middle were sparked, in part, by the decision by Sen. Kyrsten Sinema not to run for reelection, as well as Arizona's demographics and electoral history.

Had Sinema run, Lake and Gallego likely would have rushed to secure enough of their respective parties' flanks, given that the incumbent, a moderate who left the Democratic Party in spectacular fashion last year, would likely gobble up many centrist voters.

But now, both candidates are rushing to fill the void with mainstream voters who often emerge as decision-makers in Arizona elections.

The right-of-center state has more than 1.4 million registered Republicans and about 1.2 million registered Democrats -- but it also has nearly 1.4 million voters registered as "other," according to the Arizona Secretary of State's Office. And while many of the voters in that third bucket are thought to typically break for one party or the other, moderates still hold outsized sway and have blunted political aspirations of hard-liners in recent cycles, including Lake two years ago.

"How to capture those people will be the key to the kingdom," said Arizona Democratic strategist Stacy Pearson.

Both candidates, though, face headwinds as they go about their rebrands.

Lake attracted significant state and national attention during her 2022 campaign and after her loss, when she echoed former President Donald Trump's claims of election fraud to baselessly allege that irregularities cost her the race.

The high name recognition that produced -- with Noble saying "she's just tapped out" -- could make it difficult for her to shift opinions this year, especially as she continues to draw headlines over ongoing lawsuits related to her election claims.

And while she speaks about the 2022 election less, when she does, her rhetoric is largely consistent, including telling CNN last month that the race she lost was a "rigged election," a throwback to her rhetoric from two years ago.

"She was vehemently an election denier and made tons and tons of media headlines with her bombastic approach in the last election cycle. None of that stopped. She tries to pivot then falls back into her same traps," said one Arizona Democratic strategist working on down-ballot races there who spoke anonymously about the race. "She's stuck in the same argument and caricature that she made of herself from last time."

Gallego, for his part, is not as well-known as Lake, having not run for statewide office in the past or elevating to prominent levels of House leadership. He does, though, boast a progressive voting record, aligning with President Joe Biden 100% of the time, according to analysis by FiveThirtyEight.

And while he has criticized the president for not approaching the border with the seriousness he says it deserves, he spent much time hitting Trump for being too strict in his policy, a pivot on a policy issue core to the border state's voters.

"Ruben Gallego is a far-left progressive," said Garrett Ventry, a senior adviser to Lake. "The more and more Arizonans learn about Ruben Gallego, Kari Lake will pull away and win this race."

Still, operatives of all stripes indicated Lake could have a tougher time in her rebrand.

Gallego is starting off with a hefty fundraising advantage -- announcing Tuesday that he had raised more than $7.5 million in the first quarter of the year, while Lake took in $2.1 million in the last quarter of 2023. Gallego is also running in a year when an abortion referendum could make the ballot, possibly juicing Democratic turnout.

But more than that, the race could represent the rare instance in which being less known is better -- offering Gallego a chance at a reintroduction, whereas Lake could have to undergo a reinvention, some Republicans conceded.

"Insiders are aware of his flagrant trollism of his previous Twitter life. But he stopped doing that," said Chuck Coughlin, an Arizona strategist who left the GOP after Trump's election. "He's got an opportunity, because he's got a solid narrative of his life, he's got a solid opportunity to, I think, paint on an emptier canvas than she does."

"[Lake] makes these furtive attempts to do that and try to meet with people and open the tent wider, but she seems stuck in that MAGA narrative. And I don't know how she successfully undoes that after literally three years in the spotlight," Coughlin added. "Ruben, on the other hand, has a history as a committed liberal, far to the left of most of the Arizona electorate, but fortunately for him, most people don't know that."

Interviews with some Arizona voters suggested as much, with Patricia Coughlin -- Chuck Coughlin's wife and a voter who backed former South Carolina Gov. Nikki Haley in the state's GOP presidential primary -- praising Gallego's background.

"Ruben is historically progressive. But he also did serve our country. He was a Marine. I have images of him on Jan. 6, taking command, instructing and helping people put their gas masks on and evacuate. And I commend that," Patricia Coughlin said. "When push comes to shove, [Lake] will always be divisive. It'll be an us versus them."

Still, even Democrats are not counting Lake out, pointing to Arizona's history of backing Republicans and the threat that the Senate race could get swept up in the presidential contest.

"Ruben Gallego faces a threat of kind being pulled down with Biden because Biden is top-down going to affect a lot of these races," said Simran Singh, a liberal Arizona voter. "I think Kari Lake could definitely still win. Arizona still has plenty of red voters that would be willing to back her and support her who are already planning on backing Trump in this upcoming election. I think it would be silly to ignore that."