Now, after a career built on demanding attention but evading meaningful scrutiny, Donald Trump is facing accountability for the first time in his life.

Trump is struggling to respond to revelations that he pressured Ukraine to investigate former Vice President Joe Biden. And judging from his babbling public performance before reporters at the UN General Assembly in New York on Wednesday, he does not know how to cope.

As usual, the President talked about a "witch hunt" and "fake news" and popularity polls as he spoke in the hoarse voice that seems to come over him in moments of stress. Then he damaged the case for his own defense, saying that if then-Vice President Joe Biden had sought a favor from Ukraine in 2015, it would have constituted an "impeachable event."

There's no proof that Biden sought favors from Ukraine. In fact the idea that he did is refuted in original reports on the matter. But a rough White House transcript of a phone call between Trump and Ukrainian President Volodymyr Zelensky shows that the President did exactly what he'd suggested Biden had done.

"I would like you to do us a favor," Trump said to Zelensky, according to the White House transcript of the call. "There's a lot of talk about Biden's son. That Biden stopped the prosecutions and a lot of people want to find out about that, so whatever you can do with the attorney general would be great. Biden went around bragging that he stopped the prosecution so if you can look into it. ... It sounds horrible to me."

If there's "a lot of talk" about Biden's son, it has been generated mainly by the President, his supporters and his personal lawyer, former New York Mayor Rudy Giuliani. Trump told Zelensky that both Attorney General William Barr and Giuliani would be calling the Ukrainian President.

As Biden has long occupied the front-runner position in the Democratic primary, Trump has cause to fear him -- and to try to undermine him. But urging Ukraine to investigate Biden's son constitutes an abuse of the public trust.

Why would Trump use a phone call with a foreign leader to ask for a blatantly personal and political favor? I would suggest that Trump expects the government to function like his personal business -- and as a result he can't imagine that anything he might desire would be out of bounds for a president.

Throughout his life, Trump has operated under special conditions that allowed him to get away with almost anything. The classic example came when his extremely wealthy father bailed out his casino by purchasing $3.5 million worth of chips at a blackjack table and then left the casino without gambling. This gambit broke state regulations, but the resulting fine -- $30,000 -- was paltry, and the deposit provided much-needed cashflow.

Family wealth bailed Trump out of other difficulties and made it possible for him to take risks that others would have avoided. Bankruptcy followed bankruptcy , but because Trump's family money was protected by corporate structures, he maintained his high-profile lifestyle and kept on promoting himself as a super-successful businessman. He spread lies about the prominent women who had allegedly pursued him as a romantic partner, and he offered wildly varying claims about his personal wealth. Trump has even said that his net worth depends on how he feels at a given moment.

The truth about Trump remained elusive because so much of what he claimed could not be verified. His privately held businesses were not required to produce accurate public financial reports, and they never did. Meanwhile, how do you determine whether, as Trump claimed , he had once been one of the best young baseball players in New York?

As his biographer, I put time into checking Trump's claims and discovered that many, like the one about his baseball prowess, were false. These lies didn't threaten the whole country when he was just the clown prince of New York real estate and a reality TV show host boasting, falsely, about his ratings.

But now that Trump is President, all the bluster that may have seemed amusing and harmless to those who stayed outside Trump's orbit has plunged the nation into a constitutional crisis.

What we've seen in just this one Trump scandal -- and there are many more -- suggests that the President is incapable of fulfilling his duties and may even be driven by self-destructive impulses.

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As Trump acknowledged last week, a president's calls with foreign leaders are overheard by other US officials, who take notes. Given this knowledge, Trump's attempt to enlist Zelensky in his harebrained scheme was not just an abuse of public trust; it also demonstrates Trump's true beliefs about human nature. Who could be surprised that a national security official filed a whistleblower complaint about that phone call with Zelensky? Only a person who assumes that no one else ever acts out of a sense of ethical and moral duty.

What Trump seems to have ignored is that the American President operates in a system designed to check abuses -- and that the government he heads might be filled with people of conscience. As this scandal unfolds, the administration will come to learn the meaning of accountability. For Trump personally, it will be the first time.