SAN DIEGO (AP) — Former U.S. Rep. Darrell Issa, a relentless critic of President Barack Obama who retired from his increasingly Democratic district two years ago, took a step toward returning to Congress by advancing Wednesday to a runoff in one of Southern California's last conservative bastions.

Issa, 66, will face off in November against 31-year-old Democrat Ammar Campa-Najjar, who nearly pulled a major upset two years ago when he came within 3 percentage points of defeating Republican Rep. Duncan Hunter while the lawmaker was under indictment on corruption charges. Hunter was elected to six terms before resigning in January after pleading guilty to misspending campaign funds.

Updated vote totals Wednesday solidified Issa's hold on second place in the March 3 primary in the 50th District east of San Diego. With more than 185,000 ballots counted, Issa has 23% of the votes, three percentage points ahead of third-place finisher and fellow Republican Carl DeMaio. Campa-Najjar finished first with 37%. Under California's election rules, candidates from all parties run in a single primary and the top two vote-getters advance.

Issa and DeMaio, a San Diego radio host and political commentator, waged a bitter fight. They called each other liars and challenged the other's loyalty to President Donald Trump. The president did not endorse either in the primary.

Issa has since changed his tone in an attempt to win over voters who backed DeMaio and California Republican State Sen. Brian Jones. He said they “deserve credit for a hard-fought campaign" in trying to keep the seat in GOP hands.

He vowed to keep the momentum going and make that happen.

DeMaio said in an email to his supporters that he will be returning to his radio program after falling short of advancing to the runoff and that he will support the Republican candidates fighting to win California congressional seats in November, including his former foe Issa.

During the Obama administration, Issa was chairman of the House Oversight and Government Reform Committee and investigated the administration on many fronts.

Campa-Najjar was an unknown when he ran two years ago. He has moderated his platform since the 2018 campaign, emphasizing his Christian faith and gun ownership in the sprawling district where Republicans hold an 11-point advantage among registered voters. The district is home to many military veterans and includes San Diego suburbs and a swath of rural communities and farms, along with a patch of Riverside County that includes the city of Temecula.

Despite his first-place finish in the primary, It will be an uphill battle for Campa-Najjar, a small businessman and former public affairs official for the Obama administration. In Issa, he is up against a former nine-term congressman who has name recognition, a loyal following with the GOP and huge personal wealth from his time running vehicle security companies to underwrite his campaign.

Issa spent more than $2.7 million during the primary to Campa-Najjar's $1.2 million. He previously represented the neighboring coastal 49th district that includes portions of San Diego and Orange counties but was facing a tough re-election fight two years ago in the increasingly Democratic district and retired.

The disgraced Hunter, who is scheduled to be sentenced on Tuesday, stayed out of the race since leaving office. But his still-popular father, Duncan L. Hunter Sr., backed Issa. The elder Hunter represented the district for 28 years. Issa also was endorsed by U.S. House Minority leader Rep. Kevin McCarthy, a fellow Californian and close ally of Trump.

Issa campaigned as “the conservative in the race who will help President Trump enact his agenda."

That will go far in the Republican-leaning 50th, said Gary Jacobson, emeritus professor of political science at the University of California San Diego.

“It's hard to imagine an earthquake large enough that would change the outcome," he said, meaning an Issa victory.

But Democratic political strategist Bill Carrick feels the party's fortunes are changing in the 50th.

“We've seen many congressional districts move slowly but surely from strong Republican to toss up to some now that are pretty Democratic," said Carrick, who is based in Los Angeles. Indeed, Democrats took seven California GOP House seats in 2018 and now hold all but six of the state's 53 congressional seats.

Campa-Najjar intends to make an issue of Issa' running for the seat while still living in the neighboring district.

“This is the district I was born in and this is the district I will die in," Campa-Najjar told supporters last week.

Issa so far has not tried to exploit Campa-Najjar's family history as Hunter did. In a controversial ad, Hunter's campaign in 2018 suggested Campa-Najjar was an Islamic terrorist because his paternal grandfather helped plan the attack on Israeli athletes at the 1972 Olympic Games in Munich.

Campa-Najjar, who was raised in San Diego by his Catholic Mexican-American mother, never met his grandfather, who was killed in 1973 by the Israeli military. Campa-Najjar has repeatedly denounced his grandfather's actions.

During the primary, Issa was criticized for campaign ads that noted the sexual orientation of DeMaio, who is gay.

Jacobson said he doesn't see Campa-Najjar's lineage as a key issue for Issa.

“His theme will be, ‘I’m experienced and I’m a big pal of Donald Trump,’" Jacobson said.