Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

FLAGSTAFF, Ariz. — No matter who wins, Phoenix will elect its first mayor with a Hispanic surname on Tuesday.

Two Democrats, Kate Gallego, 37, and Daniel Valenzuela, 43, face a runoff after neither got 50 percent of the vote in November's nonpartisan election. Gallego led with 44 percent of the vote, followed by Valenzuela with 26 percent. (Two other candidates, Republican Moses Sanchez and Nicholas Sarwark of the Libertarian Party, but did not make it to the runoff.)

If Valenzuela wins on Tuesday, though, it would be even more historic: He would be the city's first Latino mayor.

The election concludes a campaign that has been inundated with attack ads paid for by outside groups.

Both Gallego and Valenzuela resigned their seats on the Phoenix City Council last year to run for mayor.

Gallego, whose maiden name is Widland, grew up in Albuquerque, New Mexico, the daughter of two attorneys. She went to Harvard and got an an MBA from the Wharton School. She was married to Rep. Rubén Gallego, D-Ariz., whom she met at Harvard; they have since divorced and have one child.

Among the issues Gallego champions is rebuilding the city's riverfront, bringing more biotech and manufacturing businesses to the city and expanding transportation, projects which she advanced in the City Council.

Unions United for Kate Gallego pic.twitter.com/ZcbnzVwc53 — SK8_BOARD_C (@ClaytonRasean) March 8, 2019

Valenzuela, a fourth-generation Mexican-American, is one of six and was raised primarily by his mother; according to his campaign bio, both parents died before he was 21.

He has been a firefighter for 16 years and was elected to the City Council in 2011. Among the issues Valenzuela advocates is increasing public safety, touting his involvement in hiring more police officers and helping develop community policing. He also cites his work boosting private development, which has helped in job creation.

Both Democrats are considered ideologically similar on the issues, but Gallego's progressive coalition helped her finish first for the runoff in November, and she has picked up endorsements from groups such as Emily’s List and Planned Parenthood.

The Morning Rundown Get a head start on the morning's top stories. This site is protected by recaptcha

Courting conservatives, 'dark money' messaging

To counter Gallego's lead among progressives, Valenzuela has been courting conservative voters who preferred the Republican and independent candidates in November.

Valenzuela recently picked up the endorsement of Cindy McCain, the widow of Sen. John McCain, the longtime giant of the Senate, as well as Arizona and national politics. He also picked up the endorsement of his former Republican opponent, Sanchez, and the Arizona Police Association.

This may have been the endorsement: @cindymccain Insta pic after Monday morning fundraiser downtown. #PHXMayor pic.twitter.com/zzyS6N01uR — BrahmResnik (@brahmresnik) March 8, 2019

Valenzuela has garnered the support of groups such as the city's Chamber of Commerce, whose views on issues like minimum wage increases (the group opposed it) are to the right of the Democratic candidates.

The latest headlines surrounding the last days of the race involve a flurry of ads and last-minute appeals, some of which have come under heavy criticism for their tactics as well as for misleading messaging being run by third-party interests.

For example, there is an ad for Valenzuela on Breitbart, the conservative news website whose former chairman is Steve Bannon, President Donald Trump's former strategist.

And even though both candidates are Democrats, a mailer in support of Valenzuela distributed by a political organization in Oklahoma touted him as the "conservative" choice and disparaged Gallego's support of former Democratic presidential candidate Hillary Clinton.

A mailer distributed in favor of Gallego stated that Valenzuela supported public financing for billionaire projects. While both stated their positions on the validity of the project funding, neither Valenzuela nor Gallego were on the City Council when it voted on the city ordinance. The Arizona Republic rated the ad "somewhat true/somewhat false."

The mailers, as well as a barrage of negative TV ads, have brought fresh attention to the issue of "dark money," funds used by outside groups to put out political messaging without disclosing their donors. The groups are not associated with the candidates and by law cannot coordinate with the candidates. (Not all the groups involved in the campaign attacks withhold donors.)

Gallego and Valenzuela have spoken out against the messaging, and Phoenix residents voted in November to make outside groups disclose their donors, but Gov. Doug Ducey, a Republican, hasn't signed the change yet.

City in transformation

The election highlights the complexity of a city in transformation. According to the 2010 Census, more than 48 percent of city residents were non-Hispanic whites, and 40 percent were Hispanic. Just eight years later, the latest estimates show that the number of Latinos and non-Hispanic whites in Phoenix are now almost equal; 42.5 percent Latino and 43.3 percent non-Hispanic white.

While Hispanics are considerably younger than their white counterparts, the census numbers point to Tuesday’s election as a foreshadowing of the future of Arizona politics. Among the fastest-growing cities in the country, Phoenix has been at the center of Arizona's move from a solidly red state to a budding purple one.

Arizona’s congressional delegation is majority Democrat, and the 2018 election ushered in one of the more shocking results in an election replete with them: Arizona traded in a Republican white male senator in Jeff Flake, for a bisexual Democratic woman in Kyrsten Sinema. The former mayor of Phoenix, Greg Stanton, is a moderate Democrat who defeated his Republican opponent by over 22 points to win a seat in the U.S. House of Representatives.

Given this setup, the Gallego-Valenzuela race is being closely watched outside of the state.

"Historically, it is the more progressive candidate who will win in a progressive urban election," said Luis Fraga, the director for the Institute for Latino Studies at Notre Dame.

Arizona's Latino voters are younger, however, and perhaps will not turn out heavily in an off-year election, which may help Valenzuela's center-right appeal to consolidate nonprogressive and older voters. It may be different for Valenzuela, though, when it comes to Latino voters.

"It is not unusual for Latino candidates who have some type of public safety background to feel comfortable working with conservative interests and be attractive to white voters," Fraga said, "but that rarely leads to support among Latino voters."

FOLLOW NBC LATINO ON FACEBOOK, TWITTER AND INSTAGRAM.