(CNN) James Comey thinks Donald Trump is empty, desperate for affirmation and lacks the confidence to be humble -- but he still wants him to succeed.

In a CNN town hall event Wednesday , Comey built on the devastating character sketch he has created over 10 days promoting his new book, which is evolving into one of the most damning portrayals of a sitting president in living memory.

The fired former FBI director has had 11 months to get his story straight -- and it shows. He's unflappable, never contradicts himself and has a clear narrative about his role in the 2016 election and dismissal by the President last May.

His account of his interactions with Trump adds up to a case that the former real estate magnate is morally unfit to be President -- but is also an unusually needy person -- a depiction that is staggering in its frankness.

Comey argues that Trump does not make decisions on the basis of philosophical, religious or logical considerations, but simply to assuage the deficiencies of his own character and emotional makeup.

"His only reference point is internal -- 'what will bring me what I need, what will fill this hole in me -- get me the affirmation I crave' -- that is deeply concerning," Comey told CNN's Anderson Cooper at the College of William & Mary in Virginia.

The former FBI director's damning assessments will have no material impact on special counsel Robert Mueller's Russia investigation or Trump's political fortunes.

But they might help him move more copies of the book "A Higher Loyalty."

And for Trump's supporters, the assessments are sure to be viewed as inappropriate and inaccurate and proof that the fired former FBI director is -- as the White House says -- simply whipping up controversy for profit.

Comey's depiction of the President is likely to further anger his critics who see a holier-than-thou streak in his character and believe that he is nursing his own substantial ego, even as he goes after Trump.

But his account does pry open the closed doors of the most unconventional White House in decades, and along with other insider accounts is certain to play a role in how this unusual President is remembered by posterity.

And to hear someone talking about a sitting President is such personal, derogatory terms is still remarkable.

Assertions about 'great' things

Comey portrays Trump as someone who can never think about anything but himself, how he feels.

"His style of conversation was a series of assertions about great things he had done," Comey said, describing one of his private meetings with Trump, in which he said the President made inappropriate demands for loyalty.

"The challenge I found was that they wash over you like a wave and even if you disagree, the waves keep coming."

"But that is the style, it's 'I'm great, I'm great, I'm great,'" Comey said.

The fired former FBI director says that great leaders have enough confidence to be humble and are confident in their own skin -- qualities are needed to be a great leader and which he says the President does not possess.

Instead, he said that Trump is insecure and cannot laugh.

"I saw Presidents (George W.) Bush and (Barack) Obama both use humor effectively to relax, to put at ease, to try and get to the truth. I never saw President Trump laugh even in an almost hour-and-a-half hour long private dinner," he said.

The former FBI director said that he did not have a nickname for Trump despite the derogatory monikers thrown his way by the President, like "slime ball" "Slippery Comey" and "liar" and "leaker."

"Honestly, I call him the President of the United States, because I respect the office," Comey said.

"No matter my concerns about him, I want him to be successful. I would be so happy if there is a way to peace on the Korean peninsula. We should root for our President -- that also doesn't mean we should fail to hold him accountable -- especially when he threatens our core values."

Trump's defenders, as well as arguing that Comey is grinding a personal ax because he lost his job, often also make the point that the President's critics just don't understand what makes him different and attractive to voters.

But Comey argued that the "concern is not unconventional leadership," but maintains that the way the President threatens US values. And he justifies his focus on the President's character is because it contains the roots of what he refers to a "forest fire" presidency that endangers American institutions.

"To me, what matters most, and what the American people did not vote for and would not vote for is the derogation of the norms, the touchstone of truth, which is the heart of this country," he said.

Throughout his book, Comey keeps returning to his distaste for bullies of various kinds -- in a clear hint that he also views Trump's behavior as bullying.

On Wednesday night, he gave a glimpse into an episode in his own past while he was a college student that he finds troubling.

"There was a boy that the group found irritating, and I participated in picking on him," Comey said. "Some things I did. Some things I watched. Some things I just laughed at. And I'm, 40 years later, ashamed of myself, and it taught me a lot about myself and about people in groups."