President Trump on Thursday decried the naming of a special counsel to probe his campaign’s alleged ties to Russia's election meddling as the “single greatest witch hunt” in American political history.

“This is the single greatest witch hunt of a politician in American history!” Trump tweeted.

He added that there was never such a probe into what he called “illegal acts” committed during Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE’s presidential campaign and former President Barack Obama Barack Hussein ObamaThe Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon Trump appointees stymie recommendations to boost minority voting: report Obama's first presidential memoir, 'A Promised Land,' set for November release MORE’s administration.

“With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special councel [sic] appointed!”

This is the single greatest witch hunt of a politician in American history! — Donald J. Trump (@realDonaldTrump) May 18, 2017

With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special councel appointed! — Donald J. Trump (@realDonaldTrump) May 18, 2017

Trump’s comments show the depth of his frustration over the Justice Department’s appointment of former FBI Director Robert Mueller as a special counsel to investigate Russia's involvement in the U.S. presidential election.

The tweets stand in stark contrast to the measured reaction issued Wednesday evening by the White House press office.

ADVERTISEMENT

“A thorough investigation will confirm what we already know — there was no collusion between my campaign and any foreign entity,” Trump said in the Wednesday statement. “I look forward to this matter concluding quickly.”

Trump has repeatedly blasted the Russia investigation as a politically motivated effort to undermine his election victory. He admitted that was part of the reason he fired FBI Director James Comey, who was overseeing the investigation.

“When I decided to just do it, I said to myself, I said you know, this Russia thing with Trump and Russia is a made up story, it's an excuse by the Democrats for having lost an election that they should have won,” he told NBC News last week.

But the appointment of Mueller means that probe is likely to accelerate — and venture farther outside of Trump’s control.

The move largely will take Justice Department leaders away from the sensitive probe and clears the way for Mueller to use broad powers to investigate.

The White House has long insisted there is no need for a special counsel to lead the Russia inquiry.

"This is a process that's working exactly as it should," White House press secretary Sean Spicer said Monday. "There's frankly no need for a special prosecutor."

Democrats have clamored for Deputy Attorney General Rod Rosenstein to appoint a special counsel in the wake of reports that Comey penned a memo documenting a request from Trump that he "let go" of the investigation into former national security adviser Michael Flynn.

Those concerns were heightened late Wednesday when The New York Times reported that Flynn informed Trump’s transition team he was under federal investigation for his secret lobbying work for Turkey, but was hired anyway.

The former national security adviser is also one of the figures at the center of the Russia probe. He was fired in February for misleading Vice President Pence and others over whether he discussed U.S. sanctions with Russia’s ambassador to the U.S., Sergey Kislyak.

Updated at 8:33 a.m.