Trump and Kasich exchange barbs on Twitter

This post has been updated.

Days ahead of his first campaign rally in Ohio, Republican front-runner Donald Trump went after Ohio Gov. John Kasich — on Twitter.

Beginning at a little after 8 p.m. Thursday night, Trump took to Twitter and ranted about fellow candidate, Kasich, for nearly an hour.

"I  want to do negative ads on John Kasich, but he is so irrelevant to the race that I don’t want to waste my money," read one.

By 11 p.m., the Kasich campaign had turned the Twitter frenzy into a fundraising plea, emailing supporters about Trump's "epic twitter rant" and noting: "American simply cannot afford to elect someone who isn't prepared to lead our country."

Kasich's political action committee, New Day for America, had released a new commercial Thursday morning comparing Trump and fellow outsider candidate Dr. Ben Carson to Barack Obama and his "on-the-job training for president." Politico reported Thursday night that Trump's lawyer sent letters to both Kasich and strategists from the super PAC threatening to sue the super PAC over its media campaign.

Trump is scheduled to hold a rally in Columbus Monday evening.

Some highlights from from the exchange: