Historian Douglas Brinkley, who CNN once said knew more about the presidency than any person alive, said Donald Trump's presidency has had the worst start of any administration in U.S. history.

"This is the most failed first 100 days of any president," Brinkley told the Washington Post Tuesday. "To be as low as he is in the polls, in the 30s, while the FBI director is on television saying they launched an investigation into your ties with Russia, I don't know how it can get much worse. "

Read: Donald Trump Latest Approval Rating: POTUS’ Popularity At Record Low Amid Healthcare Woes, Travel Ban

Brinkley, who is a best selling author, a professor of history at Rice University and a CNN presidential historian, made the comments after FBI director James Comey told a congressional panel his agency is conducting an investigation into possible Trump administration ties to Russia.

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Trump's approval ratings show a stark contrast between previous presidents at this point in their administration. According to Gallup, Trump had an approval rating of 39 percent during polling conducted between March 13 and 19. Other presidents had far higher approval figures in March of their first year in office: Barack Obama had a 62 percent approval rating, George W. Bush had a 58 percent approval rating and Bill Clinton had the previous lowest rating at 53 percent.

Dwight Eisenhower had the highest approval rating at in March of his first year at 74 percent, just ahead of John F. Kennedy at 73 percent.

This isn't the first time Brinkley has called the young Trump administration historically bad. Just a few days after January's presidential inauguration, Brinkley questioned whether Trump was sabotaging himself after he made dubious claims about the crowd size at his inauguration.

"The truth of the matter is he had a successful inauguration with a respectful crowd. The transition of power went off without a hitch. His supporters were amiable by and large," Brinkley told Politico on Jan. 22. "But then he can never let go and stop watching cable TV. Now he's off to the worst start of a presidency in a very long time."