"I don't think very many people take that very seriously," McCain told reporters, as quoted by the Washington Examiner. "Every day, we are all surprised by some other twist and turn of this issue so I can only respond now and now I do not think that is a rational approach."
Pressure has built on Trump since he fired FBI chief James Comey last week amid an investigation into Russia’s alleged meddling in the US electoral process. A memo reportedly penned by Comey after a February meeting with Trump suggested the president had asked him to halt a probe into former national security adviser Michael Flynn's ties to Russia.
Russia has repeatedly denied US claims that it interfered in the presidential vote, calling such allegations absurd. Kremlin spokesman Dmitry Peskov said Moscow did not have official contacts with Trump's team during the electoral campaign.