Former Rep. Darrell Issa is expected to announce Thursday that he will launch a primary challenge to embattled Rep. Duncan Hunter, R-Calif., who was indicted last year for alleged misuse of campaign funds.

Hunter won reelection in his deeply Republican district in San Diego last year less than three months after he and his wife were indicted for allegedly using $250,000 in campaign funds for private expenses. He is considered vulnerable to a primary challenge, The San Diego Union-Tribune reported.

Former Rep. Darrell Issa represented California's 49th district in San Diego and Orange County for nine terms. (Photo By Bill Clark/CQ Roll Call)

Issa announced his retirement from his North County San Diego district in January 2018 after he barely won reelection in 2016.

DARRELL ISSA LAUNCHES EXPLORATORY COMMITTEE IN POSSIBLE CHALLENGE TO REP. DUNCAN HUNTER

His seat flipped to Democrat Mike Levin in 2018.

“I believe in the American people," he said last week, according to the Union-Tribune. "I believe in the agenda of not just my party, but our current president and will do whatever I can to further that."

Rep. Duncan Hunter, representing California's 50th district, has served in Congress since 2009(AP Photo/Denis Poroy,File)

Issa previously said he would run for Hunter’s seat if his confirmation for a Trump administration trade post was stalled in Congress any longer.

“Darrell has been supportive of me in the past,” Hunter, who has not suggested he plans to leave Congress, told the Hill last June. “He is supporting me now. He is not in the district, nothing close to it. He probably doesn’t know much about the district. But it’s anybody’s prerogative to run for office anywhere they want to.”

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Hunter’s trial is scheduled for January, two months before California’s Republican primary.

His wife pleaded guilty earlier this year to one count of conspiracy.