Washington (CNN) An unsupported theory circulating on Capitol Hill and conservative media outlets about an "informant" spying on the Trump campaign reached new heights Friday morning, as President Donald Trump tweeted about the "all time greatest political scandal."

But US officials tell CNN that the confidential intelligence source was not planted inside the campaign to provide information to investigators.

One of the officials said the informant is a US citizen, but provided no other details on the identity.

The officials say that the identity of the informant had been closely held at the highest levels of the FBI and intelligence community, and the individual has been a source for the FBI and CIA for years.

Trump started the morning by taking to Twitter, quoting Fox News pundits, to call it "really bad stuff."

Read More