By Doina Chiacu and Susan Heavey
WASHINGTON, May 18 (Reuters) - President Donald Trump decried the appointment of a special counsel to lead the Russia probe as "the single greatest witch hunt" in U.S. history on Thursday, hours after he said he looked forward to a thorough investigation.
In the face of rising pressure from Capitol Hill, the U.S. Justice Department named former FBI Director Robert Mueller on Wednesday as special counsel to investigate alleged Russian interference in the 2016 U.S. election and possible collusion between Trump's campaign and Moscow.
Trump said in a statement on Wednesday night that "a thorough investigation will confirm what we already know - there was no collusion between my campaign and any foreign entity."
In a pair of Twitter posts on Thursday morning, Trump made clear he was unhappy with the latest development to roil his four-month-old administration.
"With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special councel appointed!" Trump wrote, misspelling the word counsel as he referred to former President Barack Obama and former presidential candidate Hillary Clinton.
"This is the single greatest witch hunt of a politician in American history!"
The comments mirrored a speech by Trump on Wednesday, before Mueller's appointment was announced, in which he said no politician in history "has been treated worse or more unfairly."
The decision to move to an independent probe came a week after Trump abruptly fired FBI Director James Comey, sparking a political firestorm as the agency was in the midst of an investigation into the Russia matter. Trump cited displeasure with the Russia probe as a factor in dismissing Comey.
This week, news reports alleged that Trump had previously tried to pressure Comey into backing off inquiries into former national security adviser Michael Flynn. The reports, based on a memo Comey wrote after their conversation, fueled allegations by Democrats that the Republican president may have been trying to obstruct the investigation.
Flynn's contacts with Russians during the presidential campaign, as well as his work for the Turkish government, are under investigation.
Russia has denied U.S. intelligence agencies' conclusion that it interfered in the election campaign to try to tilt the vote in Trump's favor. Trump has long bristled at the notion that Russia played any role in his November election victory, and has denied any collusion between his campaign and Moscow.
U.S. stocks fell on Wednesday as the controversy cast a cloud over prospects for Trump and the congressional Republicans' policy agenda for issues such as tax reform. A selloff in U.S. stocks looked set to extend into its second day on Thursday.
PRAISE FOR SPECIAL COUNSEL
The appointment of a special counsel to take over the Russia probe was widely praised by Democrats and Trump's fellow Republicans.
Deputy Attorney General Rod Rosenstein, who appointed the special counsel, was due to brief U.S. senators later on Thursday about Comey's removal.
Republican Representative Charlie Dent said there was no question the Russians meddled in the election. The goal of the special counsel probe, he said, was to determine whether there was collusion between Trump associates and Russia to do so.
"I believe that's why we're having this investigation - to find out if in fact there was collusion. I certainly hope there wasn't any but if there is there are going to be very serious consequences," Dent told CNN.
Another Republican congressman, Carlos Curbelo, said if any wrongdoing was uncovered, "Those people should be held accountable."
Moments before Trump weighed in on Twitter, Democratic Senator Joe Manchin welcomed the special counsel investigation and said it was important to get facts in the Russia probe.
"I am not on a witch hunt. I am on a fact-finding mission," he said on CNN.
Another Democratic senator, Dick Durbin, said he had confidence that Mueller, who is widely respected among U.S. lawmakers, will follow the facts where they lead. "This won't be a witch hunt," he said on CNN.
Durbin said Trump's actions - including the decision to fire Comey and his "incessant" provocative posts on Twitter - have done more harm than any enemy, real or perceived, could.
"This president has no one to blame but himself for the mess that he's in," Durbin said. (Reporting by Doina Chiacu and Susan Heavey; Writing by Doina Chiacu; Editing by Frances Kerry) ((email@example.com; 202-898-8322;))