WASHINGTON — Days after he predicted the president's eldest son would soon be indicted, longtime Donald Trump associate Roger Stone is appealing for contributions to a legal defense fund, saying he expects to be charged with a crime.

Stone, whose history with Trump goes back nearly four decades, says in a letter to supporters that special counsel Robert Mueller's team is "examining every aspect of my personal, private, family, social, business and political life."

The goal, Stone says, is "to frame me for some nonexistent crime to silence me and pressure me to testify against the president. ... I am not going to do it."

A spokesman for Mueller declined to comment. While it is known that many associates of Stone have come under scrutiny by the special counsel's office, it is not clear whether Stone is a target of the investigation.

Questions have long swirled about Stone's possible interactions with WikiLeaks and hacker Guccifer 2.0 during the 2016 election campaign, when both entities were releasing Democratic emails that had been hacked by Russian intelligence agents. U.S. officials have said that WikiLeaks was acting as an agent of Russia, and Mueller has labeled Guccifer 2.0 a Russian intelligence front.

Stone, who has a likeness of Richard Nixon's face tattooed on his back, has denied any wrongdoing, telling NBC News he had no advance knowledge of hacked emails.

In an Instagram video posted Monday, Stone claimed that news organizations are investigating whether he tipped off Trump that WikiLeaks was planning to post Hillary Clinton campaign chairman John Podesta's emails. Stone denies doing that.

"Someone is saying that they overheard a conversation in which I told Donald Trump in October of 2016 what exactly would be in the WikiLeaks disclosures and when they would be disclosed," Stone says in the video. "This is categorically false."

In the colorful language for which he has become known, Stone appeals in the letter for contributions to a legal defense fund.

"I need your help to fight back," he writes. "This attack on me is designed to bankrupt me and destroy me and my family financially. Mueller knows I cannot afford the expensive legal fees to defend myself. My defense cost could be more than $2 million — money I do not have."

He continues: "I intend to GO TO WAR against Mueller and his Deep State goons. Because Donald Trump is 100% innocent — and so am I!!!!"

Stone, who left his formal role in the Trump campaign in 2015, writes that "no one in America has dreamed, worked for, pushed, planned, and nurtured the idea of a Trump Presidency longer than I have."

And now, he says, "Mueller and his gang of leftist prosecutors, probably hundreds of FBI agents, and deep state lawyers and bureaucrats are coming after ME."

At least eight of his current or former employees have been interrogated by FBI agents, Stone asserts, and at least three of his associates "have been dragged before the grand jury."

NBC News has reported that Kristin Davis, a Stone friend and the former "Manhattan Madam" who helped run a prostitution ring patronized by well-heeled New Yorkers, has testified before the Mueller grand jury.

Other published reports say Stone associate Randy Credico has testified. Another Stone associate, Andrew Miller, has been held in contempt of court by a Washington federal judge for refusing to testify.

In the letter, Stone adds that "I now know Trump-targeting prosecutors have been monitoring my e-mails, text messages, and phone calls since 2016! They still have no evidence of Russian Collusion, or any other illegal activity."

Stone declined to comment for the record, but a source close to him said he was basing his assertions on surveillance on questions put to his associates about private communications with him. The source said Stone had not received a target letter like those often sent in a federal investigation when someone is about to be indicted.

He is perhaps not the most reliable narrator of his own conduct during the Trump campaign, or what government investigators are up to. After denying that he ever met with a Russian during the campaign, it emerged that in May 2016 he met in Florida with a Russian man offering to sell dirt on Hillary Clinton. Stone later admitted the meeting and said he simply forgot about it.

Stone also says twice in the letter that former Trump lawyer Michael Cohen has "flipped" and is cooperating with prosecutors. In fact. Cohen has pleaded guilty but has not signed a formal cooperation agreement. One of his lawyers, Lanny Davis, has said in television interviews that Cohen wants to help prosecutors, but whether that will happen or has happened remains unclear. Stone ends the letter by saying that "this witch hunt threatens to break me financially. Leaks by the Special Counsel's office have substantially hurt my business. I am facing millions in attorney's fees I cannot possibly afford."

Earlier this week, Stone told a conservative web site that "the special counsel is going to charge Donald Trump Jr. with lying to the FBI." It's not clear that the president's son has been interviewed by the FBI, however.

Donald Trump Jr.'s lawyers says he has done nothing wrong.