In doing so, Trump, while speaking at a rally in North Carolina, ignited fury and ridicule among some of the loudest voices in Trumpworld.

At issue among Trump's most fervent supporters is the belief that Oz, a Turkish-American TV physician who has hobnobbed with Hollywood's elite and has flip-flopped on the issue of abortion, isn't a trustworthy "America First" Republican candidate, compared to fellow candidate Dave McCormick, who has ex-Trump administration officials Hope Hicks and Stephen Miller by his side.

"I have enormous respect for President Trump. I was honored to have his endorsement in PA. Twice," Sean Parnell, the former Trump-backed candidate, who dropped out of the race after an abuse allegation surfaced from his estranged ex-wife, wrote on Twitter. "But I'm disappointed by this. Oz is the antithesis of everything that made Trump the best president of my lifetime."