Every day, it's something else. Sometimes, every hour. Just when you think Donald Trump has sunk as low as he can go, another trench opens up beneath him and he pulls his country deeper into the abyss.

In terms of the audacity of its incompetence, Mr. Trump's is a remarkable performance. But voters didn't elect the President in the hope that he would become synonymous with record-setting fatuity. They voted for Mr. Trump because he promised to make America great again. Instead, he is plunging it into constitutional crisis.

Americans now are faced with the very real possibility that the President asked the director of the FBI to stop investigating Michael Flynn, his disgraced national security adviser, after Mr. Flynn resigned from his position. That, at least, is the most logical – not to mention most disturbing – reading of an alleged private exchange between Mr. Trump and James Comey that preceded Mr. Comey's firing last week.

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The Comey firing is further complicated by allegations that, at a previous meeting, Mr. Trump had unsuccessfully asked the FBI director for his loyalty – this when the FBI was investigating possible criminal collusion between Mr. Trump's campaign staff and Russian government operatives. What does "loyalty" mean to Mr. Trump, if not a blind devotion to his interests? And so then why did he fire Mr. Comey after Mr. Comey allegedly said he could only offer the President his honesty?

All of this is based on allegations that haven't been proved, but which must be investigated by Congress. There is a debate about whether Mr. Trump's actions amount to criminal obstruction of justice, but they almost certainly constitute undue political interference with the justice system, which is an impeachable offence.

And why wouldn't these allegations be true? Mr. Trump may be a brilliant presidential campaigner, but he is a hopelessly clueless President. Authoritarian by nature, he has no understanding of, or respect for, the limitations on his power. He hires his family members for top White House jobs, lies constantly and invents wild accusations that can't be substantiated, like his claim that former president Barack Obama wiretapped the Trump Tower.

He also constantly contradicts himself. He gave one explanation for firing Mr. Comey and then changed it the next day, catching his beleaguered staff by surprise and putting them in the embarrassing position of appearing to have lied on his behalf.

Above all, he is perversely self-centred and uninterested in anything that is not about him. He is said to need constant reassurances of the greatness he believes himself to contain, and is utterly unselfaware of the existence of any flaws in his character.

Reuters reported on Wednesday that his aides have learned to put his name in every sentence of their briefing notes to him, in order to keep his attention. And a New York Times columnist this week called Mr. Trump an "infantilist" and compared his thoughts to "six fireflies beeping randomly in a jar" – a remarkably harsh attack on the personality of a president, but one that seems wholly fitting.

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Mr. Trump's puerile vanity may well have prompted him to boast last week to the Russian ambassador about highly classified Israeli intelligence that wasn't his to share. This caused a diplomatic crisis and has put America's allies on edge about trading secrets with a country whose leader is so unreliable.

There is no question that Congress must investigate every aspect of Mr. Comey's firing, in order to determine whether or not the President is trying to interfere with a criminal probe that could end his political career. It seems more and more likely that will happen.

And it's welcome news that the Department of Justice has named a special counsellor to look into the allegations of collusion between Mr. Trump's campaign and the Russians.

But regardless of the outcomes of any investigations, it's unlikely that they would lead to Mr. Trump's impeachment.

The House and the Senate are controlled by Republicans, and Mr. Trump still has the support of the party's congressional leadership. He also still has the support of the vast majority of Republican voters. Republican politicians may care about the sanctity of American democracy and believe that no person, not even the President, is above the law. But their bigger worry is that they could lose their party's nomination to another Republican candidate deemed more loyal to Mr. Trump when midterm elections are held next year.

Mr. Trump is now off on a nine-day overseas trip. It's a convenient moment to get out of the country. He'll be spending much of his trip in the Mideast, a politically charged region whose sensitivities and complexities would test any leader. First, he'll meet leaders from across the Arab world in Saudi Arabia. Then, he'll travel to Israel.

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What could possibly go wrong?