As a former White House insider, Lew told CNBC's "Squawk Box" decisions of this magnitude are made by the president. He said there have been "questions from Day 1" about who has Trump's ear and who's advice he's following. "That's not in and of itself unusual," he added. "It gets resolved at the top."
Comey's firing has
"There are challenges to
Domestically, Lew said, "The important thing here is, is there going to be an independent investigation [and] how will the American people have confidence that Russia's involvement in our election will be fully investigated?"
Calling Comey's firing "Nixonian," Democrats were quick to call for a special prosecutor over alleged Russian election interference and possible Trump campaign ties to Russia.
The "Nixonian" comparison refers to the so-called Saturday Night Massacre in 1973 when then-President Richard Nixon fired of Watergate special prosecutor Archibald Cox. The attorney general and deputy attorney general at the time resigned after refusing to dismiss Cox.
The Trump Justice Department said Tuesday's dismissal of Comey, whose agency was conducting an investigation over the Russia questions, was over the mishandling of the Hillary Clinton email investigation.
The administration said the FBI's Russia probe was not a factor in the FBI director's dismissal, but during the final days of the election, Trump had praised Comey's announcement about the Clinton probe. Clinton blames Comey's announcement for her loss to Trump.
Republicans on Capitol Hill were divided. For example, Sens. Lindsey Graham and John Cornyn defended the move. While Sens. Bob Corker and John McCain were more skeptical. McCain on Tuesday called for an independent counsel to lead the Russia probe.