Celebrity surgeon Dr. Mehmet Oz used his endorsement from former President Donald Trump during a debate Monday to ward off criticism from his GOP primary opponents that he lacks a conservative record.

Five major GOP candidates for a Pennsylvania Senate seat vied to make a last-minute impression on primary voters during Monday's debate. Former hedge fund manager David McCormick entered the debate with a small lead over Oz, and each of the candidates took turns sniping at the celebrity's past stances on abortion and gun rights.

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"The reason Mehmet keeps talking about President Trump’s endorsement is he can’t run on his own positions and his own record," McCormick argued. "The problem, doctor, is there’s no miracle cure for flip-flopping."

dr oz david mccormick

Mehmet Oz and David McCormick (Getty Images)

"President Trump endorsed me," Oz stated later on. "The first point he made about why is I’m a conservative, America-first Republican." 

McCormick and Oz were joined on stage by conservative commentator Kathy Barnette, former lieutenant governor candidate Jeff Bartos and former U.S. Ambassador to Denmark Carla Sands.

All the candidates save Bartos defended former President Donald Trump's unfounded claims that the 2020 election was rigged or stolen. 

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"I have discussed it with President Trump, and we cannot move on," Oz said of the election. "As all the other candidates up here have outlined, under the cover of COVID there were draconian changes made to our voting laws by Democratic leadership, and they have blocked appropriate reviews of some of those decisions. We have to be serious about what happened in 2020, and we won't be able to address that until we can really look under the hood."

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Republican voters will cast ballots in the primary on May 17. The winner will run against the Democratic nominee to replace Sen. Pat Toomey, who announced his retirement from the Senate in 2020.