President Donald Trump alleged Friday that the FBI planted an informer in his 2016 election campaign, stepping up efforts to cast Special Counsel Robert Mueller's Russia probe as a politically-driven "witch hunt".
"Reports are there was indeed at least one FBI representative implanted, for political purposes, into my campaign for president. It took place very early on, and long before the phony Russia Hoax became a 'hot' Fake News story. If true - all time biggest political scandal!"
On Thursday Trump tweeted about news reports on the alleged informant, suggesting it was a spying operation of president Barack Obama.
"If so, this is bigger than Watergate!" Trump said.
Trump's tweets came as the FBI remained silent on questions of whether it did have a deep intelligence informant providing inside information on contacts between the Trump campaign and Russia during 2016.
If true, the powerful law enforcement agency -- which had a sordid history in its early years of monitoring prominent politicians -- could be forced to defend itself against charges it was spying on a presidential candidate.
Last month Devin Nunes, the chairman of the House Intelligence Committee and a close supporter of Trump, demanded the FBI and Justice Department provide his committee with classified information on the informant, raising worries that the infamously leaky panel would expose his or her identity.
Hoping to avoid that, senior government intelligence officials gave Nunes and fellow Republican lawmaker Trey Gowdy a private briefing last week, at the Justice Department and FBI.
But that has not quelled the story.
Suggestions that law enforcement had an inside Trump campaign source have been around nearly as long as the one-year-old Mueller investigation into campaign-Russia ties.
Last year Trump alleged, without offering proof, that Obama had law enforcement tap communications in his Trump Tower offices in New York during the election.
Both the New York Times and Washington Post say law enforcement sources confirm the existence of a deep-cover source, used by the FBI for years in multiple investigations, who provided information on campaign-Russia contacts.
The Post reported Friday that the FBI has been working for two weeks to try and control any damage that could come if the source's identity is outed.
The FBI declined to comment Friday on the issue.
Nevertheless, Trump lawyer Rudolph Giuliani, a former Justice Department prosecutor who has worked closely on FBI investigations, told CNN Friday that they did not have any proof of an FBI informant embedded in the Trump campaign.
"We're told there were two infiltrations, two embedded people in the campaign," he said.
He said they learned that from unnamed "people," adding, "we don't know if they are right or not."
"I don't know for sure, nor does the president, if there really was. We're told that... by people who for a long time have been told there was some kind of infiltration."
The FBI "should tell us if there was," he added.