In a hilltop home near San Diego, U.S. House candidate Ammar Campa-Najjar introduced himself to a group of voters.

Like many other people running for office this election year, especially Democrats, Mr. Campa-Najjar is young, 29, and has never run for office before. Mr. Campa-Najjar, the U.S.-born son of a Mexican mother and a Palestinian father, spent part of his childhood living in Gaza in a time of relative peace.

"We'd go to the beach and eat watermelons, and smoke hookah behind our parents’ backs," he remembers. "Just genuine, innocent childhood fun."

But he also has a family connection to a violent episode in the history of the Palestinian-Israeli conflict.

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In 1972, Mr. Campa-Najjar’s paternal grandfather helped plan a terrorist attack on the Olympic Games in Munich. The attack left 11 Israeli athletes dead. The grandfather was subsequently killed by Israeli commandos.

Mr. Campa-Najjar said he shares none of his grandfather’s views and that he shouldn’t be judged for the actions of a man he never knew.

“Our lives never overlapped. He died 16 years before I was born,” Mr. Campa-Najjar said. “And so what I do know about this alleged activities, I condemn, outright, full-throatedly and without equivocation.”

But Mr. Campa-Najjar’s condemnation of his grandfather hasn’t stopped incumbent Republican Duncan Hunter from using Mr. Campa-Najjar’s family history as a political weapon.

In a recently released ad, Mr. Hunter tries to tie Mr. Campa-Najjar to terrorism.

Many critics are saying Mr. Hunter has turned to this line of attack because of his own problems.

In August, Mr. Hunter and his wife were indicted for spending more than $250,000 of campaign funds on personal expenses — including a vacation to Italy, family dental bills and video games. The 48-page indictment was handed down by a federal jury and chronicles hundreds of expenditures that prosecutors say amount to seven years of corruption.

Mr. Hunter’s spokesman has said the charges are politically motivated.

Mr. Campa-Najjar said voters’ outrage should be focused less on his family history and more on Mr. Hunter’s alleged crimes.

"He lost his way in Washington," says Mr. Campa-Najjar. "And I think there was a kind of slippery slope that he went on. It turned to self-interest and now it's leading to self-destruction."

But Mr. Campa-Najjar also said he wants to keep his campaign positive. His platform focuses on affordable health care, vocational training and clean energy, among other issues.

And when he talks to voters, Mr. Campa-Najjar emphasizes the need to get beyond today's hyper-partisanship.

“It’s not about the left vs. the right. It’s about the political machine in Washington who are duping all of us to turn on each other.”

But a lot stands in the way of Mr. Campa-Najjar getting to Congress. The 50th District, which includes rural and suburban parts of San Diego County and part of Riverside County, is conservative. Donald Trump won there in the 2016 election.

Until Mr. Hunter’s indictment, Mr. Campa-Najjar’s campaign was considered a long shot. And even in the wake of the indictment, Mr. Hunter leads in the polls.

But Mr. Campa-Najjar is counting on steady demographic changes in his district, including a growing Latino and Arab American population. The Chaldean — or Christian Iraqi — population is one of the largest outside of Michigan or Iraq, he says.

In the last few weeks of campaigning, Mr. Campa-Najjar says he's ready for political attacks that try to use his heritage or family past against him.

“I didn’t wake up and become Latino, Arab American when I started running,” he said. “So all the intrigue that comes with that and all the trials and triumphs that come with having a diverse background, and the opportunities and challenges of that, I’ve carried my whole life.”

First Published: October 14, 2018, 7:00 a.m.