Speaking to the network on Sunday, Trump's personal lawyer Rudy Giuliani said that the two camps "more or less agree on" restricting the questions to two subjects. "If everything can be worked out, then [the special counsel's office] will probably limit it to collusion and obstruction," said Giuliani, a former federal prosecutor and New York City mayor.

Mueller and Trump's legal representatives have been discussing the terms under which the president would be questioned about what he knew about Russia's interference in the 2016 election, and when he knew it.

President Donald Trump's legal team and the office of Special counsel Robert Mueller are negotiating the outlines of an agreement that could sharply limit the scope of questions the president is asked about the ongoing Russia probe, his personal lawyer told CNN.

Trump and his advocates have vigorously denied collaborating with Russia's efforts to influence the election. However, Giuliani confessed that accusations of obstructing justice – which largely focus on the circumstances under which Trump's fired former FBI Director James Comey – made him less confident.

"The obstruction part, I'm not as comfortable with – the president's fine with it, he's innocent," Giuliani told the network.

"I'm not as comfortable because it's a matter of interpretation, not a hard and fast 'true or not true. If you interpret his comment about firing Comey … as obstruction rather than removing a guy who was doing a bad job on the recommendation in part of [Deputy Attorney General Rod] Rosenstein, then you see it as obstructing the investigation.

He added: "And then you can say it's perjury, which is even easier for them which is where I think they're going."

Trump has blasted the entire probe as a partisan "witch hunt," an accusation that Giuliani raised again on Sunday. He blasted Mueller's legal team as a collection of Democrats loyal to former President Barack Obama, and Democratic nominee Hillary Clinton.