Roger Stone, the longtime ally of and former adviser to President Donald Trump, on Saturday reacted to Sen. John McCain's opposition to Trump's pardon for Joe Arpaio by tweeting that McCain was headed for eternal damnation.

"Karma about to get you, @SenJohnMcCain and you will burn in hell for all eternity," Stone wrote in a Twitter message.

McCain, R-Ariz., is battling brain cancer.

On Friday, McCain issued a statement criticizing Trump's pardon of the controversial former Maricopa County sheriff, who had been convicted of federal contempt of court.

"Mr. Arpaio was found guilty of criminal contempt for continuing to illegally profile Latinos living in Arizona based on their perceived immigration status in violation of a judge’s orders," McCain said in his statement. "The President has the authority to make this pardon, but doing so at this time undermines his claim for the respect of rule of law as Mr. Arpaio has shown no remorse for his actions.”

Stone, a controversial political operative whose long career in politics dates back to the President Richard Nixon era, currently is the subject of the 2017 Netflix documentary, Get Me Roger Stone.

In March 2016, Stone tweeted that he would be working for Kelli Ward, then a Republican primary opponent of McCain's, but nothing appeared to ever come of it.

More recently, Stone warned of violence if Trump is impeached.

"The people will not stand for impeachment. A politician that votes for it will endanger their own life," he told TMZ.

Nowicki is The Arizona Republic's national political reporter. Follow him on Twitter, @dannowicki.

READ MORE:

President Trump defends Joe Arpaio pardon

Sen. Flake gets off east at Trump rally

Arpaio opponents express outrage of Trump pardon