Democratic congressional candidate Ammar Campa-Najjar, second from left, looks on alongside a supporter, left, as the father of his opponent, former congressman Duncan L. Hunter, right, holds a news conference Tuesday, Oct. 16, 2018, in San Diego. (Gregory Bull/AP)

Rep. Duncan D. Hunter (R-Calif.), whose political future is in jeopardy after his indictment in August on charges of misusing campaign funds, is escalating his attacks on his Democratic opponent, Ammar Campa-Najjar, with a letter accusing him of being a “national security risk.”

The move comes weeks after Hunter’s campaign released a similarly-themed TV ad that The Washington Post’s Fact Checker gave four Pinocchios for its false or misleading claims and its “naked anti-Muslim bias.”

Signed by three retired Marine Corps generals who currently work as lobbyists, the Hunter campaign letter warns voters of a “security alert” and states that Campa-Najjar “has close family connections with the very jihadist groups our troops are operating against.”

“If he should get elected and sees secret information on U.S. military operations that would endanger members of his Najjar family in the Middle East, would he compromise U.S. operations to protect his relatives, the Najjars?” the letter asks.

Campa-Najjar, a Christian, was born in San Diego and raised by his mother and her Mexican American family. The 29-year-old Democrat’s grandfather, who died 16 years before he was born, was a key planner of the 1972 attack on Israeli athletes at the Munich Olympics. Campa-Najjar has condemned the attack.

Campa-Najjar’s father is a former Palestinian Authority official; the candidate was estranged from him for a time while he was growing up.

The Campa-Najjar campaign responded by pointing out that the candidate held a security clearance from 2013 to 2017, when he worked at the White House and later at the Labor Department, whereas Hunter “would not be able to obtain a security clearance today” because of his criminal indictment. The Campa-Najjar campaign described the Hunter campaign letter as “xenophobic and race-baiting.”

“Mr. Hunter’s ongoing attacks on me, his wife, and the Justice Department aren’t just political; they’re pathological,” Campa-Najjar said in a statement. “While Hunter has no human sense of personal accountability, voters understand his family is not responsible for his actions, and I’m not responsible for my family’s actions.”

In a television interview this summer, Hunter appeared to shift the blame to his wife for his alleged wrongdoing. He has also lashed out at the Justice Department, which he called “the Democrats’ arm of law enforcement.”

Mike Harrison, a spokesman for Hunter, confirmed that the letter was printed and is being distributed by the congressman’s campaign. He disputed the notion that the letter was stoking fears that are based on the Democrat’s ethnicity.

“This matter has absolutely nothing to do with our opponent’s heritage and absolutely everything to do with Ammar Campa-Najjar’s known, existing, personal relationships with the PLO and the Council on American-Islamic Relations,” Harrison said.

The Post’s Fact Checker has previously found no evidence that Campa-Najjar’s campaign had received donations from the Council on American-Islamic Relations, a 501(c)(3) entity that is barred from donating to or supporting political candidates.

The ad comes as Campa-Najjar’s fundraising is booming while Hunter’s is sputtering. Campa-Najjar raised $1.4 million in the third fundraising quarter and has about $685,000 cash on hand.

Hunter, meanwhile, raised a little over $132,000 during the same period and has about $247,000 on hand. Among those giving to Hunter’s campaign was Donald J. Trump for President, which made a $2,000 donation on Aug. 17, five days before the lawmaker was indicted.

Following Hunter’s indictment, House Speaker Paul D. Ryan (R-Wis.) said that the lawmaker would be “removed from his committee assignments pending the resolution of this matter.” With Ryan retiring at the end of his current term and his successor as Republican leader yet to be determined, Hunter’s future in the House remains uncertain.

In addition to the letter signed by the three retired generals, the Hunter campaign has distributed fliers featuring a photo of Hunter, a Marine veteran, in his military uniform. An image of the flier viewed by The Washington Post did not appear to include a disclaimer, required by Department of Defense policy, that “neither the military information nor photographs imply endorsement by the Department of Defense or their particular Military Department.”

Hunter’s campaign has come under scrutiny for previously failing to include such a disclaimer in its TV ads.

Harrison did not comment specifically on the flier but maintained that Hunter’s campaign “has always consistently utilized the appropriate disclaimers on all our distribution material.”

Other literature distributed to residents of the district includes a black-and-white flier that ominously warns of the “Najjar Family’s Trail of Terror.” The Hunter campaign did not respond to a request for comment on whether it was responsible for the ad.

Salvador Rizzo and Paul Kane contributed to this report.