Sean Hannity turns on surging GOP candidate as Trump tries to get her rival Dr Oz over the line in Senate primary

Opponents have begun airing ‘Crazy Kathy’ ads to attack the candidate

Republican Pennsylvania Senate candidate Kathy Barnette is facing heat from influential Republicans — including Fox News host Sean Hannity — now that she's surged to a front-runner position just days before the state's primary.

GOP operatives backing celebrity talk show host Dr Mehmet Oz's candidacy have circled the wagons and begun attacking Ms Barnette to try to hobble her ahead of the primary, NBC News reports.

On Thursday, former President Donald Trump weighed in, launching an attack on Ms Barnette to try to boost the chances of his preferred candidate, Dr Oz. He did hedge his bets, however, and said he would support her if she did win.

“Kathy Barnette will never be able to win the General Election against the Radical Left Democrats,” Mr Trump said in a statement. “She has many things in her past which have not been properly explained or vetted, but if she is able to do so, she will have a wonderful future in the Republican Party — and I will be behind her all the way.”

Ms Barnette would be Pennsylvania's first Black senator if she is elected.

While Dr Oz and hedge fund executive Dave McCormick battled for the primary seat, Ms Barnette flew largely under the radar. She landed a major endorsement from a Club for Growth Action, a conservative organisation which spent $2m for commercials boosting her candidacy.

Those opposing Ms Barnette have begun airing an ad calling her "Crazy Kathy," which includes clips of the candidate talking about "systemic racism," particularly "among police officers."

The video tries to suggest she supports Black Lives Matter in an attempt to weaponize racial animus in the Republcian base.

Ric Grenell, a former Trump official, has been trying to help Dr Oz by dredging up old tweets Ms Barnette made asking for prayers because she reportedly saw a homosexual woman on an airplane.

Fox News host Sean Hannity has also been badgering Ms Barnette to talk to him. Thus far, Ms Barnette has dodged his requests, and likely with good reason; Hannity is an outspoken supporter of her opponent, Dr Oz.

On his show, Hannity also showed some of Ms Barnette's old tweets while Dr Oz was appearing as a guest. Hannity said Ms Barnette was unelectable.

“I concur with your diagnosis,” Dr Oz said when Hannity asked for his response. “She is a mystery. Barnette won’t answer questions about her record, but what I do know concerns me."