President Donald Trump's lawyer, Rudy Giuliani, has raised eyebrows by claiming that "truth isn't truth" during a television interview.
Mr Giuliani was arguing that Mr Trump should not testify to the Russia probe, as he might be "trapped into perjury".
"Truth is truth", NBC host Chuck Todd countered. Mr Giuliani denied this was the case, and said two rival versions of events were in contention.
His reply seemed to echo controversial claims from Trump aides about facts.
In January last year Kellyanne Conway told Todd's programme, Meet the Press, that the White House was entitled to present "alternative facts" - to which Todd retorted: "Alternative facts are not facts. They're falsehoods."
The exchange on Meet the Press on Sunday began with Mr Todd asking Mr Giuliani whether the Trump team was stalling about a possible testimony at the inquiry led by Special Counsel Robert Mueller into alleged meddling by Russia in the 2016 US election.
Mr Giuliani said: "I'm not going to be rushed into having him testify so he can be trapped into perjury."
He added: "When you tell me that he should testify because he's going to tell the truth and he shouldn't worry, well that's so silly because it's somebody's version of the truth. Not the truth."
Todd responded: "Truth is truth." Mr Giuliani said: "Truth isn't truth."
The interviewer put his hand on his forehead and said: "This is going to become a bad meme!"
Mr Giuliani then made his main point - that accusations of obstruction of justice against the president hinge on a conversation he had with then FBI director James Comey in February 2017, and that Mr Trump's account of that conversation differs radically from Mr Comey's.
"If you're just a genius, tell me what the truth is!" Mr Giuliani tells Todd. "We have a credibility gap between the two of them. You've got to select between the two of them."
Trumps critics were prompt to seize on the exchange. Preet Bharara, a Democrat who was fired as federal prosecutor by the Trump administration, suggested "truth isn't truth" would not sound convincing in a trial.
Rudy Giuliani: “Truth isn’t truth.” Try that one with a jury. https://t.co/LEexBm5YEw— Preet Bharara (@PreetBharara) August 19, 2018
Others shared Todd's sense of disbelief.
This is not the first time that Mr Giuliani, a former New York City mayor, has spoken of irreconcilable accounts of the same event.
He told the Washington Post in May that Mr Mueller and his team "may have a different version of the truth than we do."
In the interview, Mr Giuliani characterised the Russia inquiry as "wild, crazy, unorthodox".
The president denies any collusion, and has repeatedly called the Mueller probe "a witch hunt".
Russia also denies claims it interfered in the polls two years ago, which saw Donald Trump defeat Democratic rival Hillary Clinton.