FILE - Kathy Barnette takes part in a forum for Republican candidates for U.S. Senate in Pennsylvania at the Pennsylvania Leadership Conference in Camp Hill, Pa., Saturday, April 2, 2022. Several prominent conservative groups are getting involved in Pennsylvania's race for U.S. Senate and backing candidate Barnette as an alternative to Mehmet Oz, the celebrity heart surgeon endorsed by former President Donald Trump. (AP Photo/Matt Rourke, File) Kathy Barnette
FILE - Kathy Barnette takes part in a forum for Republican candidates for U.S. Senate in Pennsylvania at the Pennsylvania Leadership Conference in Camp Hill, Pa., Saturday, April 2, 2022. Several prominent conservative groups are getting involved in Pennsylvania's race for U.S. Senate and backing candidate Barnette as an alternative to Mehmet Oz, the celebrity heart surgeon endorsed by former President Donald Trump. (AP Photo/Matt Rourke, File)

While Dr. Oz has Donald Trump’s endorsement, the anti-tax Club for Growth and the anti-abortion Susan B. Anthony List are backing Barnette.

HARRISBURG — Dr. Mehmet Oz hardly has a commanding lead in the primary race for Pennsylvania’s US Senate seat. And now, one of his rival candidates is gaining ground and endorsements.

Several prominent conservative groups are getting involved and backing Kathy Barnette as an alternative to Oz, the celebrity heart surgeon endorsed by former President Donald Trump.

The anti-tax Club for Growth endorsed Barnette on Wednesday and has begun airing TV ads on her behalf. That follows the anti-abortion Susan B. Anthony List’s decision on Tuesday to back Barnette over Oz.

“Kathy is a courageous advocate for life who exposes the human cost of abortion,” Marjorie Dannenfelser, the president of Susan B. Anthony List, said in a statement.

At least week’s GOP Senate debate, Barnette questioned Oz’s credibility as an anti-choice candidate, bringing up a 2019 radio interview where Oz seemed to criticize the idea of banning abortion just because a heartbeat is detected — which usually happens at around six weeks of pregnancy. 

Barnette’s umbrage with Oz on the abortion topic took a personal tone, as she described being the byproduct of rape when her mother was 11.

“I was not just a lump of cells,” Barnette said. “As you can see, I’m still not just a lump of cells.”

It’s unclear whether the endorsements and advertising will be enough to carry Barnette to the top of the field in Pennsylvania’s May 17 primary.

The Club for Growth, for instance, unleashed millions of dollars in advertising against Trump-backed JD Vance in Ohio’s GOP Senate primary earlier this month only for the “Hillbilly Elegy” author to go on and win the race by an eight-point margin.

But the growing focus on Barnette suggests anxiety among some conservative and pro-Trump circles that Oz doesn’t sufficiently reflect their views on abortion, guns, or the culture wars the GOP is waging against Democrats.

An Oz loss next week would mark another setback for Trump after his preferred candidate for governor was defeated in Nebraska’s Republican primary on Tuesday.

Trump remains the most popular figure among Republican voters and his endorsement helped pull Vance to victory in the final weeks of the Ohio campaign. Both Trump-backed congressional candidates also won in West Virginia’s primary.

A Fox News poll released Monday, however, suggested a tight race in Pennsylvania’s Senate election.

The poll found 22% of GOP primary voters supported Oz with former hedge fund CEO David McCormick and Barnette bunched together at 20% and 19%. About one-fifth of voters, or 18%, said they were undecided.

If elected, the 50-year-old would be the first Black woman Pennsylvanians sent to the US Senate.

She came into the race with little name recognition or money, but gained support among some right-wing groups by campaigning with allies of Trump’s baseless conspiracy theories that Democrats stole the 2020 election in Pennsylvania.

Barnette’s 2020 loss to Madeleine Dean in the race for Pennsylvania’s 4th Congressional District sent the former educator-turned-conservative pundit on a quest to uncover election fraud in Montgomery County

While she found zero evidence, some feel the conspiracy theories Barnette floated lit the fuse that sent Trump on a frenzy about voter fraud in the commonwealth, and prompted state Republicans’ “forensic investigation” into Pennsylvania voter information. 

In recent years, she has become a speaker for anti-abortion causes, penned a memoir about being Black and conservative, and gained a platform as a guest on conservative news shows.

Until recently, Pennsylvania’s Senate race has been primarily an expensive duel between Oz and McCormick. Both candidates and the super PACs that support them have reported spending more than $50 million and have blanketed Pennsylvania’s airwaves with TV ads.

McCormick and Oz have largely stayed quiet in public about Barnette, who has raised and spent a fraction of that money.

But Barnette has criticized both as carpetbaggers and “globalists,” slammed Oz as a liberal and taken aim at what she called the GOP’s habit of electing “the richest person.”

She also has dismissed Trump’s endorsement of Oz, saying Trump’s Make America Great slogan, or MAGA, “does not belong to President Trump. MAGA, although he coined the word, MAGA actually belongs to the people.”

The other major race in Pennsylvania, for its open governor’s office, is also volatile for Republicans, with party leaders and movement conservatives fearing that a far-right candidate will win it.

That candidate, Doug Mastriano, and Barnette often campaign together, along with key figures in Trump’s circle who have spread denialism about the 2020 election, including Trump’s former national security adviser, Michael Flynn, and lawyer Jenna Ellis.

Associate editor Patrick Berkery contributed to this report.