Trump lashes out at Lindsey Graham: He's 'shown himself to be beyond rehabilitation'
The Economist Intelligence Unit ranked victory for Republican presidential candidate Donald Trump at 12 on an index where the current top threat is a Chinese economic "hard landing" rated 20 (AFP Photo/Jim Watson)

Donald Trump's battle with Republican mainstays continued on Friday as he ripped Sen. Lindsey Graham (R-SC) for refusing to support his presumptive presidential nomination.

"While I will unify the party, Lindsey Graham has shown himself to be beyond rehabilitation," the real estate mogul said in a statement. "And like the voters who rejected him, so will I!"

The latest installment in the war of words between Graham and Trump started when, as Talking Points Memo reported, Graham refused to support either Trump or Democrat Hillary Clinton.

"He lost me when he said my friend John McCain was a loser because he was captured as a P.O.W," the senator said. "He lost me when he accused George W. Bush of lying to the American people about the Iraq War. And he thinks Putin's a good guy."

While he respected people who could "go there," Graham said, he could not. He also offered Trump "congratulations."

"You did a hell of a thing. You beat me and everybody else," he said. "I just really believe that the Republican party has been conned here."

Trump seized on Graham's poor showing in the GOP primary field in his response, saying his lack of support in South Carolina showed he had "zero credibility."

"If I got beaten as badly as I beat him, and all the other candidates he endorsed, I would not be able to give my support either," Trump's statement read. "Every time I see Lindsey Graham spew hate during interviews I ask why the media never questions how I single-handedly destroyed his hapless run for President."

The scrap with Graham came a day after Trump chided House Speaker Paul Ryan (R-WI) for not immediately pledging support to him, saying, "I am not ready to support Speaker Ryan's agenda."