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CNN —  

Former Rep. Darrell Issa launched an exploratory committee to run for a congressional seat now held by another California Republican, Rep. Duncan Hunter, who is facing federal corruption charges.

“I have formally launched an exploratory committee for the 50th Congressional District in California,” wrote Issa on his campaign website. “I have received such a tremendous outpouring of encouragement from supporters inside the district, and around the state and across the Nation. I’m truly grateful for the many encouraging phone calls, messages and letters that I have received.”

Issa, the former chairman of the House Oversight committee, was a constant gadfly to the Obama administration, overseeing investigations and contentious hearings into the attack on the US embassy in Benghazi, Libya, and on the Internal Revenue Service’s targeting of conservative groups, amid other issues.

Last year, President Donald Trump nominated Issa to run the US Trade and Development Agency.

The nomination seemed to stall for months, but Senate Foreign Relations committee chairman Jim Risch told CNN in August that he planned on holding a hearing on it in September, saying Issa was well qualified for the role.

In 2000, Issa was first elected to the House. He served until he decided not to seek reelection last year. Issa, one of the wealthiest members of Congress, represented a Southern California seat that flipped to the Democrats along with a handful of others in 2018. His old district adjoined Hunter’s, a safer seat for a Republican.

In June, Hunter’s wife Margaret pleaded guilty to conspiring with her husband to “knowingly and willingly” convert more than $200,000 in campaign funds for personal use. She has agreed to cooperate with prosecutors.

Hunter, a Marine Corps veteran, has served in the House since his election in 2008, when his father retired and gave up the seat. He has asserted that he and his wife were targeted by the Department of Justice for political reasons.

California’s filing deadline for the race is in early December.

CNN’s Maeve Reston contributed to this report.