Former Trump campaign adviser Roger Stone sent out an email Tuesday asking supporters to help him raise $500,000 to clear his name of any wrongdoing in the investigation of Russian interference in last year's presidential election.

"Friend, I'm facing a $500K price tag to clear my name of the Deep State's baseless charges!" the flamboyant Republican consultant wrote in his fundraising appeal, which asked supporters to contribute from $25 to "even $100 or more immediately."

Stone wrote that the "legal assault" against him has already cost him more than $100,000 in legal fees.

Stone has not yet been charged with anything by special counsel Robert Mueller or accused of anything by the three congressional committees conducting Russia probes. Mueller and the committees are investigating possible collusion between the Trump campaign and Russian officials.

Stone testified behind closed doors in late September before the House Intelligence Committee. Rep. Adam Schiff of California, the senior Democrat on the panel, said afterward that Stone might face subpoenas for refusing to answer questions about "one significant area."

Stone told reporters that he declined to tell the committee who had served as his intermediary with WikiLeaks founder Julian Assange.

House investigators quizzed Stone about his advance knowledge of WikiLeaks' release of a slew of embarrassing emails from the account of Hillary Clinton campaign chief John Podesta in the midst of the presidential race.

Stone made cryptic references via Twitter about the expected publication of damaging information related to Podesta just two months before the emails were released. Stone said he wouldn't tell committee members who served as his intermediary with Assange because it was a journalist and their conversation was off the record.

Stone rejects the Intelligence Community's conclusion that Clinton's campaign and the Democratic National Committee were hacked, arguing that the emails were leaked by someone inside the campaign and amounted to "an inside job."

"But the Deep State Democrats who hate President Trump and need an excuse for the internal failures and disastrous results of Hillary's campaign keep coming after us," Stone wrote. "The President and I are under assault!"

Last month, Stone was suspended from Twitter after an expletive-filled tweetstorm attacking CNN and some of its news anchors.