Donald Trump is threatening to sue fellow GOP presidential rival John Kasich over the latter's rumored plan to unleash a blistering $2.5 million attack on the Republican front-runner via a super PAC.

According to Yahoo, the swirling rumors prompted Trump to respond with a flood of tweets, in which he lambasted the Ohio governor. At one point he taunted, "Governor Kasich, whose failed campaign and skills have brought him way down in the polls, is going to spend $2.5 million against me."

And Trump was just getting started, firing off a dozen or so tweets, in which he also boasted, "John Kasich, despite being Governor of Ohio, is losing to me in the Ohio polls. Pathetic!"

Finally, Trump posted, "Watch Kasich squirm---if he is not truthful in his negative ads I will sue him just for fun."

Reports are Trump's lawyer Alan Garten has already fired off a letter to New Day for America super PAC officials, warning he plans to take swift legal action on behalf of his client should they find fault with the validity of any of the claims made in the ads.

The Trump Organization took similar action back in September, when top officials sent a cease-and-desist letter to conservative group Club for Growth after the pac ran attack ads against Trump in Iowa.

Late Thursday, New Day chief strategist Matt David showed no signs that the group was intimidated by the bombastic real estate mogul.

"Mr. Trump's been successful in suing his way to financial gain," he said. "Unfortunately, you can't sue your way to the Oval Office."