China is smack in the middle of the campaign spotlight in the increasingly combustible Republican Senate primary in battleground Pennsylvania's consequential and expensive race, as two of the leading contenders keep taking aim at each other over an issue that's top of mind with many GOP voters.

"First China sent us COVID. Then David McCormick’s hedge fund gave Chinese companies billions. We got sick. China got investments and David McCormick got rich," the announcer in a new TV ad by Mehmet Oz charges. "McCormick. China’s friend. Not ours." 

As McCormick, a former hedge fund executive, jumped into the increasingly crowded primary race last month, his former hedge fund’s considerable investments in China instantly came under scrutiny from Oz, one of his top rivals.

PENNSYLVANIA GOP SENATE BATTLE: MCCORMICK JOINS CROWDED FIELD OF CONTENDERS

McCormick, a West Point graduate, Gulf War combat veteran and Treasury Department official in former President George W. Bush's administration, steered the hedge fund behemoth Bridgewater Associates from 2017 through the end of last year. And during his tenure as CEO, the hedge fund made investments in China.

Just ahead of his entry into the race, American Leadership Action, a super PAC supporting well-known celebrity physician known as Dr. Oz, fired up ads claiming "David McCormick, he’s a friend — of China, with a long record of selling us out." 

Now, the Oz campaign has gone up with an ad of their own targeting McCormick over his China ties. The Oz campaign told Fox News they’re spending six figures to run the commercial statewide in Pennsylvania on broadcast and cable TV.

WATCH DAVID MCCORMICK'S FOX BUSINESS INTERVIEW 

McCormick, in an opinion piece on FOX Business as he launched his campaign last month, vowed that, if elected, "I will do everything in my power to end our dependence on China, protect our communities and our jobs, counter their attempts to reshape the world in their authoritarian image, and ensure America remains the world’s unrivaled military and economic superpower."

Pointing to his tenure during the Bush administration, McCormick touted during a recent interview on FOX Business’ "Mornings with Maria": "I’ve negotiated with the Chinese as a government official. I had a reputation for being a very tough-minded negotiator to the point that the Chinese were pushing back to the president on the policies I was making under the Bush administration."

"If you think about the kind of people we need, we need people that actually understand and can put forward a tough-minded set of polices with China and that’s what I’ll do," he argued.

LISTEN TO DR. OZ ON FOX NEWS' ‘THE BRIAN KILMEADE SHOW’

In an interview a couple of hours later with Fox News Digital, McCormick took direct aim at Oz, the cardiac surgeon and author who until the launch of his Senate campaign late last year was host of TV’s popular "Dr. Oz Show."

"I’ve been in the race for 12 hours, and they’re already telling lies about me and Mehmet Oz is telling lies about me. He’s pretending to be an outsider, but I can’t think of a more DC insider play than lying to benefit yourself," McCormick charged.

The Oz campaign, responding to McCormick’s fiery comments, noted a November Wall Street Journal report that Bridgewater Associates – while McCormick was still CEO – raised the equivalent of $1.25 billion for its third Chinese investment fund, boosting the hedge fund firm "into the ranks of the biggest foreign managers of private funds" in China. 

Asked about the investments, McCormick acknowledged in the FOX Business interview that "more recently Bridgewater has done business with China, but I have been a person throughout my business has been very focused on negotiating with the Chinese."

And the McCormick campaign noted that Bridgewater has investments all over the world, with less than 2% of the firm's revenues coming from China.

MCCORMICK TAKES AIM AT CHINA IN FOX BUSINESS OP-ED

Responding to the new ad, the McCormick spotlighted Oz’s dual citizenship with Turkey and questioned why some of Oz’s merchandise was made in "Chinese factories."

"Mehmet Oz – citizen of Turkey, creature of Hollywood – has spent the last 20 years making his fortune from syndicating his show in China, enriching itself through censorship and CCP propaganda," McCormick campaign spokesperson Jess Szymanski charged.

"While Mehmet has been silent on China until he needed to knock down Dave’s credentials, Dave was serving our country and standing up to the CCP. Voters of the Commonwealth of Pennsylvania have a right to ask why Cleveland, Ohio-born Mehmet Oz won’t renounce his Turkish citizenship and why he chose to serve in the Turkish military over America’s military. How can he claim to be America First when he has dual loyalties?" Szymanski argued.

Oz, who as a dual citizen is legally permitted to serve in Congress, has indicated he has no intention of renouncing his Turkish citizenship. And Oz’s campaign has repeatedly pointed to an opinion piece the candidate wrote in which he said he’s kept his Turkish citizenship to make it easier to visit family, including his mother, who lives in Istanbul and suffers from Alzheimer’s. In his op-ed, Oz also noted that he has "deep concerns about many of its (Turkey’s) authoritarian polices and harmful foreign policies."

The Oz campaign fired back following the statment from McCormick's team.

Campaign spokesperson Brittany Yannick told Fox News that "this is a disgusting attack against Dr. Oz. He maintains his dual citizenship to oversee the care of his mother, who has Alzheimer's. McCormick knows this and the attack on a son standing with his mother has no place in public discourse. McCormick should be ashamed of himself."

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Talk of taking a muscular approach to U.S.-Chinese relations and curbing Beijing’s influence is a message most Republican voters want to hear, and many GOP candidates running in the 2022 cycle are spotlighting the issue. 

McCormick and Oz are two among many GOP candidates who would gladly welcome an endorsement by former President Donald Trump – who remains very popular with Republican voters as he continues to play a kingmaker’s role in party politics and flirts with a 2024 White House run. And they've spotlighted their support for the former president’s America First policies, which included a confrontational stance against China.

McCormick and Oz are two of the leading candidates in a crowded field of Republican contenders aiming to succeed retiring GOP Sen. Pat Toomey in a race that could decide whether the Republicans win back the Senate majority in November’s midterm elections.

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Among the other leading GOP candidates are a real estate developer, philanthropist and 2018 Republican nominee for lieutenant governor, Jeff Bartos; real estate executive and major Republican donor Carla Sands, who served as ambassador to Denmark under Trump; and veteran and conservative political commentator Kathy Barnette.

The candidate Trump had endorsed in the Pennsylvania GOP primary race, Sean Parnell, ended his bid in November immediately after he lost a bitter fight for custody of his three children to his estranged wife, who in court testimony had accused Parnell of abuse. Trump has indicated he’ll weigh in again in the crucial Senate race. As first reported by Fox News last month, Parnell, an Army veteran who saw combat in the Afghanistan War, endorsed McCormick.

The race has quickly become one of the most expensive Senate showdowns in the country. 

The national ad tracking firm AdImpact tells Fox News that over $15 million has already been spent by the campaigns and outside groups to run ads, with Oz and McCormick the biggest spenders to date among the candidates.