Harris County Sheriff Adrian Garcia is sending every possible message that he intends to run for mayor this year, aggressively increasing his political operations and signaling to some close advisers and backers that a campaign may be imminent.

Garcia, under the Texas Constitution, would have to resign as a county official immediately upon declaring his candidacy. That presents Garcia, who watchers expect to immediately move to the field's top tier if he joins the burgeoning mayoral fray, with a fateful decision: Does he step down as the county's top Democratic officeholder to make a bid that would make him either Houston's first Latino mayor, or politically unemployed?

"At the end of the day, it's like standing at the craps table, placing the bet - and you could walk away with nothing," said Garcia confidant Greg Compean.

It is a bet Garcia allies said this week he has grappled with and seems willing to make.

"I'd be really surprised if he didn't," Compean said.

The sheriff was not available for comment Thursday, his political adviser said.

Garcia, who said last week he still is listening to others and has not yet officially committed to the race, has met with many of the city's political leaders in advance of an announcement and privately is telling some close allies that he will run. And other evidence is mounting.

The sheriff spent $350,000 in the last six months of 2014, according to his campaign finance report released last week. That sum, spent in a year when he was not on the ballot and 10 times what he spent during the last six months of 2010, nearly depleted the coffers of his political action committee, which, under city ordinance, may not be allowed to transfer more than $10,000 to a mayoral bid.

The report also revealed that Garcia had hired new fundraising and digital advertising shops, along with spending $100,000 on tele-town halls, some of it after last November's election, that gave him a chance to reach and gather data on up to 500,000 voters. Garcia's political operation also hired an analyst to parse through that data.

This month, he commissioned a poll to gauge his viability, people with knowledge of the poll said.

Garcia also slowly has been building his profile locally and nationally: He was invited to the White House in November to discuss immigration policy. He has continued his high-octane social media presence and leveraged it to build an email list. And he spent a fair amount of money this cycle giving to the Democratic interest groups that can help decide future elections, noted Marc Campos, a Houston Democratic strategist not committed to Garcia.

"The only way to explain spending all that money is to let everybody know that he's a good Democrat," Campos said. Garcia likely did so to remind them that of all the candidates that have a Democratic base, he was the one who was working the hardest this past November, Campos said.

Staff eyeing opportunities

Perhaps most tellingly, county sources say, is that Garcia's top staff at the Sheriff's Office are looking to jump as they eye other county positions that would give them a landing place beyond Garcia's tenure and vest them in the county's pension system. Garcia's top lieutenant and close friend, Armando Tello, left last month for a lower-profile post in Precinct 6, and other executive officers currently are scoping out other opportunities.

"He's running," said Hispanic Chamber of Commerce head Laura Murillo, who once considered her own bid for mayor. "He's getting ready to make his announcement very soon."

Murillo is not in Garcia's inner circle, but several of the sheriff's other allies confirmed a bid is all but inevitable.

Former Houston mayor Bill White, who long has mentored Garcia but said he has not committed to any candidate, said the sheriff told him he was "seriously considering" the race in a visit at the end of the year.

"I did sense a gleam in his eye that was like a racehorse that wanted to go on the track," White said.

To a certain extent, that race already has begun. Ever since a federal judge declared Houston's fundraising blackout period unconstitutional two weeks ago, all but one of the eight candidates running for mayor have scrambled to contact donors and set up the political infrastructure to accept those contributions.

Meanwhile, Rep. Sylvester Turner, who political observers see as the current front-runner, is sidelined from fundraising until June, when the Legislature's still-on-the-books blackout period expires.

Nonpartisan appeals expected

Every day that Garcia sits the race out is one day less that he has to raise the $2 million most experts say any candidate would need to run a serious campaign and catch Turner, who will try to transfer much of the $1 million he already has in his state representative campaign account

Backers of Garcia have high hopes he could raise the money to compete and that he could win voters beyond Houston's Latinos, who comprise more than 40 percent of the city but at the most only 15 percent of the electorate. The county's highest vote-getter in 2012, Garcia is expected to make appeals to some Republican voters in the nonpartisan election.

Garcia also would open himself up to personal attacks over a yearlong political brawl. Some in political circles for months quietly have questioned whether Garcia, who has no college education, can handle the rigors of the city's top job. And if he resigns as sheriff, some Democratic judges and Latino leaders worry whether the party and the Hispanic community would be hurt without him leading the local ticket.

Harris County Commissioners Court is almost certain to replace Garcia as sheriff with a Republican, although one Democrat, Constable Alan Rosen, is said to be interested. Constable Ron Hickman and Rep. Allen Fletcher are considered the most viable replacements.

Even if his seat flipping would upset the Democratic hands who labored to elect and re-elect him, his donors and backers in the Latino community seem to be carrying more weight.

"You got to put our best foot forward," said Massey Villarreal, a Hispanic Republican who has been pushing Garcia to run. "I think I've got him on the 5-yard line."