Three years before Joe Martinez made official his intentions to run for Miami-Dade mayor in 2012, Juan C. Zapata began raising money to seek Martinez’s commission seat.

Martinez’s aspirations were no secret, and Zapata, then a state lawmaker friendly with Martinez, says the incumbent commissioner urged him to get an early start on the race.

The long campaign has put Zapata in a strong fundraising position in the three-man, nonpartisan contest to replace Martinez in District 11, which encompasses a swath of unincorporated west Miami-Dade, including the neighborhoods of Country Walk, the Hammocks, Kendale Lakes and Lakes by the Meadow.

The battle for the only open seat on the commission this year also includes political newcomers Manny Machado, a Miami-Dade police detective, and Javier Muñoz, a network engineer at Florida International University.

Zapata has raked in far more in campaign contributions than his opponents, with Machado in second place and Muñoz a distant third. But Muñoz, for one, says he set out to run a grassroots race with close friends and family to introduce himself to voters as a fresh face.

“I am the proverbial political outsider,” Muñoz said. “You see a lot of politicians that jump from seat to seat to seat, and they’re just being politicians and not making any significant impact.”

Zapata, who represented a portion of the district as a Republican in his eight years in the Florida House, says he sees himself more as a community activist who turned to politics to get things done.

“I’ve taken tough votes against my party,” said Zapata, a self-described social moderate who advocated for immigrants and helped create a Hispanic legislative caucus in Tallahassee. “I’ve never sold out the interests of this community.”

Machado, 37, did not respond to repeated interview requests for this story. His police personnel file shows he is on leave from the department while he’s running for office. His campaign website does not include a biography but says he has been in law enforcement for 12 years and is married with two children.

Muñoz, a married 29-year-old, has never run for office before but said he has long been interested in politics. He graduated from G. Holmes Braddock Senior High School and received his bachelor’s degree and master’s in business administration from FIU, where he works in computer infrastructure. Part of his job is to manage large projects — experience, he said, that would help him on the commission.

“My background and education level will help me, I think, rein in and control the excessive debt that has been going on in a number of capital projects,” he said.

Zapata, who is 45 and unmarried, was born in Peru to Colombian parents. He lived in Medellín until moving to west Miami-Dade with his parents and sister when he was 11.

He has long worked as an entrepreneur, running businesses ranging from seafood distribution to mattress delivery, and founding the nonprofit Colombian American Service Association. He is a partner in a local condo-management firm and works as a business-development and public-affairs consultant, though he said his clients are mostly in Latin America, Texas and Puerto Rico, and not in Miami-Dade.

After being elected to the West Kendall Community Council, where he served for two years as chairman, Zapata ran for the county commission in 2000. He lost in the first round of the election and endorsed Martinez in the runoff. Martinez returned the favor, backing Zapata early on in the current commission race. Focused on his own campaign, however, Martinez, who shares a campaign manager with Machado, has largely kept his distance from the contest.