Bret Jaspers/KJZZ

Phoenix mayoral candidates Kate Gallego and Daniel Valenzuela.

Kate Gallego opened a large lead over Daniel Valenzuela early in the race for Phoenix mayor on Tuesday.

Though the race is officially nonpartisan, Gallego and Valenzuela are both Democrats who largely agree on most issues but faced off bitterly on funding for sports arenas and public safety. Both are former council members who gave up their seats to run for mayor of the fifth-largest U.S. city.

With unofficial results showing her up by 17 percentage points, Gallego declared victory before supporters at a downtown Phoenix restaurant.

Phoenix election officials said Tuesday night more than 124,000 ballots have been counted, and they will continue to process ballots over the next several days.

City of Phoenix

Early election results posted by Phoenix at around 8 p.m. on March 12, 2019.

RESULTS: Phoenix Unofficial Special Election Results

Valenzuela conceded in a post on Twitter.

"Thank you, Phoenix. I appreciate all you've done for me," he wrote. "Tomorrow morning I will continue to serve you as a lifelong public servant. Congratulations to our next mayor, @KateWGallego."

Gallego said her focus as mayor will be economic development for the city.

"My background is in economic development, and I really want to push this city to be a knowledge economy based city, high wage jobs. So, that's my real passion."

She said she's thinking about the long-term projects for the city.

"I want to think about the kind of city I want to leave for my son and all of Arizona families, so that means taking on projects that won't be done before the next election," she said. "I hope to do things like build the South Mountain technology corridor or take our riverfront and redevelop it. Tempe took their riverfront on the Salt River and created the Tempe Town Lake. City of Phoenix can think big and think long term about our riverfront."

Outside groups — some without disclosing their donors — unleashed a barrage of attack ads in the final days of the campaign.

Gallego responded to the attack ads on Tuesday night.

"We ran a positive campaign. I talked about my vision and where I wanted to go...and I think voters rewarded that," said Gallego. "They said no to 'dark money.' In the last two weeks, we received a record number of expenditures against us from an organization in Oklahoma that doesn't disclose its funding and the voters said, 'No, we're not going to respond to these negative attacks.'"

The winner will finish the term of former Mayor Greg Stanton, a Democrat who was elected to Congress in November.

Gallego, 37, is a graduate of Harvard and the University of Pennsylvania business school who worked at the Salt River Project utility before turning to politics. She'd be the second woman elected to lead the city after Margaret Hance, a Republican mayor from 1976 to 1983. Thelda Williams, who is leading the city until the election, has been interim mayor three times.

Valenzuela, 43, is a firefighter in the neighboring city of Glendale. A Phoenix native, Valenzuela grew up poor with a mostly absent father. He would be the first Latino mayor of Phoenix.

Gallego led Valenzuela by a wide margin in the primary, when the field of candidates was narrowed to two. Since then she's come under a barrage of attacks by outside groups backing Valenzuela.

One ad funded by police and fire unions accuses Gallego of voting against money for public safety because she opposed a 2016 property tax increase. Gallego said the money should come from a fund for sports facilities, not property taxes.

She and her supporters attacked Valenzuela's support for stadium subsidies for the Phoenix Suns and Milwaukee Brewers, which conducts spring training in west Phoenix's Maryvale neighborhood.

Home to 1.6 million people, Phoenix has seen its population rebound since thousands moved away after the Great Recession hit the economy especially hard. Downtown has seen a revitalization with new apartments, condos and businesses.

The next mayor will confront rising housing prices and a growing number of police shootings.

Phoenix Special Election - March 12, 2019