US President Donald Trump has lashed out at the decision to appoint a special counsel to oversee the inquiry into Russian influence on his election.
"This is the single greatest witch hunt of a politician in American history," he tweeted on Thursday morning.
His reaction differed from Wednesday when he was quoted in a White House statement as saying: "I look forward to this matter concluding quickly."
Former FBI director Robert Mueller has been selected to lead the inquiry.
In naming Robert Mueller, the US deputy attorney general said it was in the public interest to pick an outsider.
Mr Mueller's appointment has been welcomed by politicians from both sides.
Calls for a special investigation mounted after Mr Trump fired FBI Director James Comey last week.Mueller 'is ramrod straight in integrity'How powerful is the special counsel?
"With all of the illegal acts that took place in the Clinton campaign and the Obama Administration, there was never a special councel [sic] appointed," he tweeted on Thursday.
He later reposted the same tweet, after correcting his misspelling of the word "counsel".
A number of times previously, Mr Trump has likened the investigation into potential collusion between his campaign and the Russian government to a witch hunt.
His latest tweets came hours before he was to hold a joint press conference with the visiting Colombian president.
On Wednesday, Mr Trump said no politician in history "has been treated worse or more unfairly" than himself.(Source: BBC)