Trump's friend and lawyer Rudy Giuliani told Fox News host Sean Hannity on Wednesday night that Comey was fired because he refused to publicly announce that the president was not under investigation in the Russia probe.

The comment from press secretary Sarah Huckabee Sanders came in response to the latest justification to emerge from within Trump's inner circle, almost exactly a year after Trump made the fateful decision that triggered the appointment of special counsel Robert Mueller.

President Donald Trump's decision last year to fire FBI Director James Comey does not require any justification, the White House said on Thursday, because the president has the authority to hire and fire whomever he wants.

"There are a number of reasons why James Comey was fired. The president has named several of them," she said. "But the bottom line is he doesn't have to justify his decision. The president has the authority to fire and hire, and I think that every single day, we've seen that he made the right decision in firing James Comey."

Pressed by reporters, Sanders snapped that Comey was fired, "for lying, leaking and politicizing the FBI," before adding, "The president has repeatedly been proven to be exactly right in his decision to fire James Comey."

The exchange underscored the fact that nearly a full year after Comey was dismissed, the White House still lacks a cohesive explanation of what was behind Trump's decision. That question is now at the center of a far-reaching probe into whether or not Trump committed obstruction of justice by firing Comey, who was overseeing what was then an FBI investigation into potential Russian meddling in the 2016 election.

Giuliani's interview Wednesday night marked the first time that a member of Trump's inner circle blamed Comey's firing primarily on his refusal to publicly exonerate the president in the Russia probe.

"He fired Comey because Comey would not — among other things — say that he wasn't a target of the investigation," said Giuliani, "even though he had done the same thing for Hillary. So you can't blame the president for feeling, 'I am not being treated the same way they were.'"

A few days after Comey was fired, Trump said in a televised interview that he was thinking about the Russia probe when he decided to terminate the FBI director.

"When I decided to just do it, I said to myself, I said, 'You know, this Russia thing with Trump and Russia is a made-up story," he told NBC News' Lester Holt.

This reason was at sharp odds with the official White House line, which said that Comey had been fired for mishandling a 2016 investigation into Trump's opponent, Hillary Clinton.

Comey later told investigators that Trump asked him to drop an ongoing FBI investigation of National Security Advisor Mike Flynn, whom Trump fired just weeks after he was inaugurated. Comey also said that Trump demanded a pledge of loyalty from the FBI director.

When Comey refused Trump's requests, their relationship soured, according to Comey. Trump has denied the former FBI boss's accounts.

Giuliani recently joined Trump's legal team, tasked with negotiating a potential interview between Trump and special counsel Robert Mueller.