DALLAS — Guadalupe “Lupe” Valdez was making the rounds in jeans and a purple blouse on a recent Sunday at Norma’s Cafe, a popular diner packed with a diverse mix of Texans.

“Hey, sheriff!” exclaimed a Latino in a Dallas Cowboys jersey, and Valdez was soon at his side, grinning.

“I was afraid people wouldn’t recognize me without the uniform,” she said.

The week before, Valdez — the state’s first openly gay and first Latina sheriff, with almost four terms under her belt as Dallas County’s top cop — announced she was resigning to run for governor. In a crowded Democratic primary, she’s the front-runner with the potential to boost party voter registration and turnout long-term, especially among Latinos. Though Valdez is unlikely to beat Republican Greg Abbott, a popular governor in a red state with $50 million to spend, she could benefit from a backlash against President Trump, mobilizing Latino voters.

“We’re giving people hope,” Valdez said. “A lot of people have written off Texas.”

Valdez, 70, is no stranger to adversity. She grew up in San Antonio, the youngest of eight children in a Mexican American family, migrating with her parents to work the fields. She waited tables to put herself through Southern Nazarene University, then joined the Women’s Army Corps. She was not openly gay at the time, but had friends who were gay or were spotted at gay bars and dishonorably discharged as a result.

She came out later in life, in stages: living more openly in the 1990s, attending a gay-friendly church, working for the federal government and worrying less about the career implications as she rose through the ranks, becoming a senior agent with the Department of Homeland Security in 2002.

When she retired and ran for sheriff in 2004, she was out of the closet, but even with the voter turnout boost of a presidential election she was a long shot.

“She ran for sheriff in a county that did not have a single countywide official that was a Democrat and hadn’t for 20 years. She ran against an incumbent sheriff. She did not have any experience running for office. Few people, if any, gave her any chance of winning,” said Texas Democratic Party Chairman Gilberto Hinojosa.

Valdez won by a slim margin, 51% to 49%. But her win helped set the stage for a larger victory, attracting Democratic candidates who swept into office in 2006. Two years later, Valdez’s margin of victory widened, 55% to 45%. Last year, she was reelected by the widest margin yet, 59% to 37%. As Dallas’ population grew and diversified, one of the keys to those victories was turning out minority voters, she said.

Valdez, who announced last month that she was resigning as sheriff to run for governor, said her campaign would be focused on economic issues that concern blue-collar families and the elderly, those who worked their way up like she did, subsisting at times on peanut butter and jelly, making sure they paid the rent, cleaned up for church and prayed over their meals the way she and others did at Norma’s.

“She understands what those folks are going through, what they need, what their families are all about,” Hinojosa said. “The only reason Texas is not a blue state is because the huge Latino population in this state has not turned out the way it should and the way it has in states like California.”

Wendy Davis, the Democrat who ran against Abbott in 2014, lost by more than 20 percentage points, a setback for Democrats statewide. She had risen to national prominence as a state legislator filibustering for abortion rights.

“One hope that Democrats have for Lupe Valdez is that she increases voter registration and turnout among Latinos and she shifts the percentage of the Latino vote won by Democrats from the 55[%] to 65% range, where it’s been recently in Texas, to the 65[%] to 75% range, where it’s been in places like California,” said Mark Jones, a political science professor at Rice University in Houston.

Democrats now have two paths to relevance in Texas, Jones said: Peel off moderate, white Republican voters or mobilize their base, especially Latinos.

Andrew White, 45, a Houston entrepreneur and son of the late Democratic Gov. Mark White, represents the first path. Valdez represents the second.

Valdez, though openly gay, is “not defined by her sexual orientation” the way Davis was defined by her stand on abortion, Jones said: “She’s not Harvey Milk.” Her girlfriend, a Dallas chiropractor, doesn’t plan to make many appearances on the campaign trail. Where Davis looked like a model, Valdez said, she looks like a “grandma.”

Texas Republican Party Chairman James Dickey believes Valdez’s record on “sanctuary” cities and other issues makes her unpalatable to Texas moderates. He noted that when liberal Democrat Leticia Van de Putte ran for lieutenant governor in 2014 against conservative fellow state Sen. Dan Patrick, a tea party stalwart, she lost by a wide margin, 39% to 58%.

“There was a limited appeal as far as identity, and at the same time a massive disconnect on values, issues and principles,” Dickey said. “No moderate of any race who looks at Lupe’s track record would consider her a moderate.”

Dickey also doesn’t expect Valdez to benefit from a Trump backlash at the polls. “I will be shocked if we do not have a statewide candidate this election that wins straight up a majority of the Hispanic vote, because it’s our issues that resonate with all Texans,” he said.

Former Dallas County Republican Party Chairman Jonathan Neerman disagreed.

“Traditional Latino Republican voters could abandon the party because of Trump and vote Democrat, or the sleeping giant could awaken and new Latino voters could vote Democrat,” Neerman said.

In that way, Valdez would lay the groundwork for another Democrat to stage a successful campaign for governor in 2022, Jones said, such as San Antonio congressman Joaquin Castro or his twin brother, former U.S. Housing secretary and San Antonio Mayor Julian Castro.

Democrat Tony Sanchez managed to dramatically boost Latino turnout when he ran for governor against Republican Rick Perry in 2002, Jones said, but the party missed the chance to capitalize on that four years later.

“What Lupe Valdez is going to try to do is engage the Latino community that 2018 is a steppingstone,” Jones said. “The key for Democrats will be that the Valdez candidacy is not a one-off, that it sets things up for another candidate in 2022.”

molly.hennessy-fiske @latimes.com