Story highlights The Russia investigation is just in the early stages but has already deeply wounded the Trump presidency, writes Julian Zelizer

And it could get worse, Zelizer says

Julian Zelizer, a history and public affairs professor at Princeton University and a CNN political analyst, is the author of "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." He's co-host of the "Politics & Polls" podcast. The opinions expressed in this commentary are his own.

(CNN) President Donald Trump lives in the biggest political bubble of all. His disastrous last few weeks culminated with former FBI Director James Comey delivering stinging testimony about how the President leaned on him to stop a major investigation into the administration.

Testifying before the Senate Intelligence Committee, Comey expressed his strong feeling that the President is an inveterate liar who could not be trusted. President Trump ended his brief Twitter hiatus by saying: "Despite so many false statements and lies, total and complete vindication . . . and WOW, Comey is a leaker!"

At his press conference Friday in the Rose Garden, Trump doubled down by saying: "Yesterday showed no collusion, no obstruction." Trump, who said he would testify under oath to deny Comey's claims about their conversation, added that the testimony was an "excuse by Democrats" who lost an election "they shouldn't have lost." More fake news from President Trump.

Trump's strident sense of confidence about his invulnerability in the expanding investigation is a result of the President being surrounded by weak "yes" men and women as well as being defended by a conservative media which spins every story his way.

When he turns on the television, there is at least one pundit ready to repeat the talking points that his own White House puts out. Ironically, President Trump's skewed world view also gains support from disillusioned Democrats, still reeling from the election, who think of him like President Frank Underwood from "House of Cards," the guy who gets away with everything.

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