WASHINGTON -- Mark this down as a campaign first: Donald Trump "doxed" Sen. Lindsey Graham. In a rambling speech knocking Graham for calling him a “jackass,” Trump read the senator’s cell phone number out loud at an event that was being covered by national news networks.

When it comes to campaigns, there tends to be a certain level of accepted courtesy regarding your opponents. And one of those courtesies tends to be not releasing your opponents' cell phone numbers in a public setting.

But Trump -- who has become the target of much of the rest of the GOP field as he’s skyrocketed to the top spot in the polls -- isn’t one to pay much attention to campaign niceties. Speaking to a crowd in South Carolina -- the state Graham represents in the Senate -- Trump was full of attacks against the longtime incumbent.

“In the private sector, he couldn’t get a job,” Trump said to a roomful of people whom Graham represents. At another point, Trump said, "I think Rick Perry is smarter than Lindsey Graham."

He then told a rambling story about the time Graham asked him for help. He said Graham asked him to go on Fox News and give him a good reference. And then, Trump said, Graham asked him if he would make a campaign contribution.

Then Trump produced a small square of paper which he said was where Graham had once written down his personal cell phone number. He read the number out loud. “Give it a shot, your local politician. He won’t fix anything but at least he will talk to you,” Trump told the crowd.

Graham’s campaign was quick with a response. “Donald Trump continues to show hourly that he is ill-prepared to be commander in chief,” Graham campaign manager Christian Ferry said. “The two people most excited about Donald Trump's candidacy are Barack Obama and Hillary Clinton. 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.”

Social media then erupted. Many people attempted to call Graham, getting his voicemail. One reporter even got him to answer.

Trump's newest row with Graham comes only a few days after Trump ignited a storm of criticism from fellow Republicans when he suggested that Arizona Sen. John McCain isn't a war hero because he was taken captive. Graham and McCain are close friends in the Senate.