The investigation into Russian interference into the 2016 presidential election isn't just focused on criminal acts. Worried about the president's erratic behavior and the firing of FBI Director James Comey, the FBI opened an inquiry into President Trump directly, a new report says.

The counterintelligence investigation that examined if Trump was working for Russia, now part of the inquiry special counsel Robert Mueller took over when he was appointed, was rolled into Mueller's investigation because if Comey's firing was aimed at ending the Russia investigation, it needed to be investigated both as a possible crime and a national security concern, the New York Times reported.

While Mueller's inquiry has led to the indictment of dozens of people, including close Trump advisers such as campaign chairman Paul Manafort, his former personal attorney Michael Cohen, and former national security adviser Michael Flynn. Mueller has yet to conclude his investigation.

White House press secretary Sarah Sanders called the report "absurd."

"James Comey was fired because he's a disgraced partisan hack, and his Deputy Andrew McCabe, who was in charge at the time, is a known liar fired by the FBI," Sanders said.

