Republican House candidate Mike Garcia is likely to claim a win in the special election to replace former Rep. Katie Hill, D-Calif., who resigned last year after an ethics probe was opened amid bizarre allegations she maintained a "throuple" relationship with her husband and a campaign staffer, and that she also had an improper sexual relationship with one of her congressional staffers.

Garcia didn't declare victory on Tuesday night as he built a double-digit lead in a race against Democrat Christy Smith to succeed Hill in California's 25th Congressional District, and Smith didn't concede. But it appears likely that Garcia will be the next representative from California in a year many in the GOP believe they can grab a majority in the House of Representatives in the November elections.

An incomplete tally showed Garcia with about 56 percent of the vote, with 143,000 ballots counted.

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Here's what to know about Garcia.

He's a veteran

Garcia, according to the biography on his campaign website, attended the U.S. Naval Academy after graduating high school in 1994. He then attended the Navy's flight school in 1998. Garcia was a F/A-18 pilot who participated in Operation Iraqi Freedom in 2003 and logged more than 1,400 in the cockpit.

"My operational service in the Navy was the pinnacle of a career. While my family made great sacrifices the reward of serving our country and providing for its defense was well worth it," Garcia said.

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He's a former executive at a major defense contractor

Following his service in the Navy, Garcia joined Raytheon, one of the largest defense contractors in the U.S., according to his campaign website and a Linkedin profile in his name. There, he was a vice president of business development after working his way up from a middle management position, he says on his campaign site.

"At Raytheon, I learned the intricacies of doing business with the Pentagon, the Presidential and Congressional Budget drills that lead up to the signing of the NDAA (the National Defense Authorization Act is the annual bill that ultimately funds the military thru Congress), and I further advanced my awareness of all national security issues domestically and abroad," Garcia says.

He added that his time at Raytheon led him to realize that the way the military buys its weapons and other goods is "broken" due to "inefficiencies."

He comes from a police and military family

According to Garcia's campaign website, his stepfather was an officer in the Los Angeles Police Department and a veteran of the Vietnam War.

Garcia says his stepfather was one of the most "influential" people in his life and "taught me about service," "discipline and hard work."

This undated photo provided by the Mike Garcia For Congress campaign shows candidate Mike Garcia. A swing House district north of Los Angeles is up for grabs in a contest that will be an early test for President Donald Trump as he heads toward November. Trump has been using his presidential perch to summon up support for Republican Mike Garcia in a special election for the vacant 25th District seat. (Cynthia Smalley/Mike Garcia For Congress via AP)

This undated photo provided by the Mike Garcia For Congress campaign shows candidate Mike Garcia. A swing House district north of Los Angeles is up for grabs in a contest that will be an early test for President Donald Trump as he heads toward November. Trump has been using his presidential perch to summon up support for Republican Mike Garcia in a special election for the vacant 25th District seat. (Cynthia Smalley/Mike Garcia For Congress via AP)

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He was backed by a major GOP super PAC

The Congressional Leadership Fund, a major super PAC that boosts Republican House candidates, poured $600,000 into Garcia's race in its final month. That support, according to a release from the CLF, took the form of direct mail efforts and digital ads attacking Garcia's opponent, Smith.

"Times of crisis show a person’s true character," CLF President Dan Conston said in a statement referencing Smith's time as a school board member. "For Christy Smith, that meant firing hardworking public school teachers while giving herself a raise... Californians need the proven and steady leadership of Navy fighter pilot Mike Garcia to lead our country out of these turbulent times – not another career politician only looking out for herself, like Christy Smith."

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He studied at Georgetown

Garcia, if he does in fact win this election, would share an alma mater with a rather large percentage of the D.C. political establishment.

While he was still at the Naval Academy in Annapolis in 1998, he picked up a master's degree in National Security Studies at Georgetown University.

Fox News' Gregg Re and the Associated Press contributed to this report.