U.S. President Donald Trump raised the firing of the FBI director in a meeting with Russia's foreign minister to explain why he had been unable to find areas of cooperation with Moscow, two top administration officials said on Sunday.

"The gist of the conversation was that the president feels as if he is hamstrung in his ability to work with Russia to find areas of cooperation because this has been obviously so much in the news," National Security Adviser H.R. McMaster said on ABC's "This Week with George Stephanopoulos" program.

On the "Fox News Sunday" show Secretary of State Rex Tillerson said Trump was also trying to convey to the Russians that he was "not going to be distracted by all these issues at home that affect us domestically."

Tillerson and McMaster were present at the May 10 meeting between Trump and Russian officials during which he discussed his firing of James Comey, the former director of the Federal Bureau of Investigation.

The New York Times, citing officials familiar with an internal White House summary of the meeting, reported that Trump referred to Comey as a "nut job" and said his removal would relieve "great pressure" coming from the agency's probe into Russian meddling in the 2016 presidential election.

Former FBI chief Robert Mueller was named special counsel last week to investigate alleged Russian interference in the 2016 U.S. election and possible collusion between Trump's campaign and Moscow.

The controversy has shadowed the first foreign trip by Trump, who was in Riyadh on the first leg of a nine-day trip that includes Israel, the Vatican, a NATO meeting in Brussels and the Group of Seven summit in Sicily.

Republican U.S. Senator John McCain of Arizona told "Fox News Sunday" he was left "speechless" by reports of Trump's remarks about Comey in the May 10 meeting with Sergei Lavrov, the Russian foreign minister and Sergei Kislyak, the Russian ambassador to the United States.

"I don't know how to read it except that, I'm almost speechless because I don't know why someone would say something like that," McCain said, adding that the president should never have met with the Russian officials.

Comey is set to testify before the Senate Intelligence Committee in two weeks. Senator Marco Rubio, a Florida Republican on the panel, told CNN's "State of the Union" program on Sunday he would ask the former FBI director whether he ever felt pressured to not do his job.

"If any president tries to impede an investigation – any president, no matter who it is – by interfering with the FBI, yes, that would be problematic. That would be not just problematic, it would be obviously a potential obstruction of justice that people have to make a decision on," Rubio said.

Rubio emphasized that he will reserve judgment until he has seen all the evidence and heard from sources, including Comey.