Here's Carl Bernstein:
'It came from a former British MI6 agent who was hired from a political opposition research firm in Washington who was doing work about Donald Trump for both republican and democratic candidates opposed to Trump.
'They were looking at Trumps business ties, they saw some questionable things about Russians, about his businesses in Russia, they in turn hired this MI6 former investigator, he then came up with additional information from his Russian sources, he was very concerned by the implications of it, he then took it to an FBI colleague that he had known in his undercover work for years, he took it to this FBI man in Rome who turned it over to the bureau in Washington in August.
'And then, a former British ambassador to Russia independently was made aware of these findings and he took the information to John McCain – Senator John McCain of Arizona – in the period just after the election, and showed it to McCain – additional findings.
'McCain was sufficiently disturbed by what he read to take it to FBI director James Comey himself personally, they had a five minute meeting the two men, very little was said, McCain turned it over to him and is now awaiting what the FBI’s response is to that information.'
Numerous media sources have said they've been shopped the story -- but they couldn't corroborate it.
That's mediaspeak for: this is bullshit.