US President Donald Trump has hurled a new set of insults at James Comey, challenging accusations the former FBI director makes in a tell-all book that is due for release this week, and insisting that he never pressed Mr Comey to be loyal to him.
"Slippery James Comey, a man who always ends up badly and out of whack (he is not smart!)," Mr Trump wrote in one of five Twitter posts aimed directly at the fired FBI chief.
The renewed attacks by Mr Trump came as US ABC News was set to air an interview with Mr Comey (at 12:00pm AEST) in which he discusses his book, A Higher Loyalty.
Mr Trump fired Mr Comey last May, setting off a firestorm, as the Federal Bureau of Investigation was probing possible connections between Mr Trump's 2016 presidential campaign and Russia's meddling in the American elections.
Russia has denied interfering in the election and Mr Trump has denied any collusion or improper activity.
Reuters and other news outlets have obtained copies of Mr Comey's book before its formal release this week.
In it, Mr Comey wrote that Mr Trump, in a private meeting, pressed the then-FBI director for his loyalty.
The FBI has long tried to operate as an independent law enforcement agency.
Mr Trump disputed the claim on Twitter.
US House of Representatives Speaker Paul Ryan, interviewed on NBC's Meet the Press, expressed qualified support for Mr Comey.
Mr Ryan, asked whether Mr Comey was a man of integrity, said, "as far as I know" but added that he did not know him well.
Asked about Mr Trump's use of the words last week "slime ball" to describe Mr Comey, Mr Ryan said, "I don't use words like that".