At an event here, Trump claimed that Graham called him a few years ago to ask for money and to get a reference to appear on the show “Fox and Friends.”
"I am saying to myself, 'What's this guy, a beggar?'" said Trump, before reading his number to the crowd.
Trump brought up Graham, who has been very critical of him, seven times during the speech, delivered characteristically without notes.
Graham's campaign confirmed that the number Trump gave out belongs to the senator. A call to the number went to voicemail, with a female voice indicating the number belonged to Graham.
If Trump was looking for a way to muck up Graham's primary form of communication, he might have found it. Graham says he does not use e-mail and still carries a flip phone.
After Trump’s 45-minute stemwinder, he walked to an overflow room with a few hundred more people.
“People are tired of incompetent leadership,” he said. “They’re tired of the Lindsey Grahams of the world.”
Asked why he gave out Graham’s personal cellphone number, Trump said from the passenger seat of his black SUV: “So people can call him; so he can get something done.”
In a statement, Graham campaign manager Christian Ferry said Trump is a gift to Democrats.
"The two people most excited about Donald Trump's candidacy are Barack Obama and Hillary Clinton," Ferry said. "Because of Trump's bombastic and ridiculous campaign, we aren't talking about Obama's horrible deal with Iran or Hillary Clinton's plans to continue Obama's failed national security agenda."
Trump has come under heavy criticism from his own party, most recently for disparaging the military record of Sen. John McCain (R-Ariz.). Graham and McCain are close friends. In an interview with "CBS This Morning," Graham called on Trump to "stop being a jackass."