On Tuesday, Trump's presidential campaign released a "cease and desist" letter sent by the billionaire's general counsel, Alan Garten, to Club for Growth President David McIntosh.
In the letter written on the letterhead of Trump's business conglomerate, Garten says the conservative group has misrepresented Trump's views on taxes by taking an old statement that he would like to hike taxes across the board on the "superwealthy," a view that Trump's campaign claims he no longer holds.
Like most things in Trump's campaign, the letter does not conform with traditional legal language.
His counsel addresses the Club for Growth at one point as "your pitiful little group" and another as the perpetrator of a "shake-down" — the group earlier in the year asked for a $1 million donation from the billionaire businessman, which he declined.
The letter said "we will not sit idly by and allow special interest groups and political action committees like yours to defame Mr. Trump and cause damage to his reputation and business interests."
The correspondence closes with an ultimatum: 
"In the interest of avoiding what will certainly be a costly litigation process, we are prepared to offer you the one-time opportunity to rectify this matter by providing us with your prompt written assurances that (i) you have stopped running the Attack Ads; and (ii) you will not generate or disseminate any misleading or inaccurate information or make any factually baseless accusations... with respect to my client at any point in the future."
If the Club for Growth refuses to heed Trump's warnings, the the real estate mogul's counsel threatens: "we will commence a multi-million dollar lawsuit against you personally and your organization ... as well as pursue all other remedies available to us at law or in equity."
Club for Growth Action released a statement on Tuesday afternoon responding to the Trump organization's letter saying the ad campaign will continue.
“Tough guy Donald Trump starts whining when his liberal record is revealed,” said McIntosh. “Trump has advocated higher taxes numerous times over many years, just like he’s advocated for universal health care, the Wall Street bailout, and expanded government powers to take private property. 
"Trump’s own statements prove that our ads are accurate. They will continue to run. We suggest that Donald grow up, stop whining, and try to defend his liberal record.”
On Sep. 15, the group's political arm held a press conference at the National Press Club in D.C. to announce it was launching a $1 million advertising campaign in Iowa, branding Trump “the worst kind of politician.” 
The two advertisements highlight Trump’s past statements that he identifies as a Democrat and that he has supported using eminent domain to take private property. Trump, one of the ads says, is “playing us for chumps.”