Boris Johnson can write a newspaper column almost in his sleep. He writes quickly, often on deadline, and in the torrent highly amusing copy pours out. The columns are – in the words of one of my fellow former Daily Telegraph comment editors – great shaggy dog tales, containing entertaining diversions and loops back to the beginning, before he pulls it all together with a “shucks folks” final paragraph or two.

They stand in marked contrast to standard political leader columns – “the leader writes” – which are usually written by advisers and are almost always unreadable. No-one reads them, not even their own husbands and wives, as my old editor used to say. Part of Boris’s attraction, in contrast, is that he writes his own stuff and it usually zings. The readers forgive the ideological contradictions in exchange for entertainment. His columns make you smile. They are immensely readable.

But they are not, it turns out, the best vehicle for a potential Prime Minister to lay out his stall on how he plans to run the country.

On Sunday for Monday, Boris wrote a newspaper column that will go down in history, but possibly not for the reasons he imagined when he wrote it. It read for a start as though it had been written by committee. Parts of it looked as though they had almost nothing to do with Boris.

Worst of all, it was a too blatant and failed exercise in trying to square the circle of his leadership of the Leave campaign. Not a natural “outer” (he is pro-European, but a Brussel’s sceptic) he had to work his way back from the robust campaign rhetoric to something which can win him the support of pro-Remain Tory MPs and form the basis for a successful negotiation with the EU. This is work that is best done carefully, and by aides and supporters explaining to colleagues why the position has evolved, before it culminates in a considered and statesmanlike speech. A 1200 word newspaper column written in a hurry is not the place to try this manoeuvre.

It seems that the highly confused and implausible Boris version of Leave that emerged in that Daily Telegraph column helped convince Michael Gove that he should challenge Boris for the leadership, or rather it gave those who want to stop Boris the ammunition to persuade Gove that Boris cannot do it. Team Boris is pointing out that Gove read and helped edit the Boris column before it went to press, but that does not preclude him having pushed it through while having doubts.

Whatever the bizarre behind the scenes machinations, the column suggested Boris was again trying to have his cake and eat it, arguing nothing would change on free movement post-Brexit for example. When it landed the column produced a flicker of unease in the Tory tribe, even among people who think of Boris as a winner. Has he thought this through? Can you envisage him negotiating with Merkel? Is government by newspaper column sustainable, so that we must all buy the newspaper concerned every Monday to find out – exclusively – where we are all headed?

Boris carrying on being a columnist was always going to be a problem for his campaign. He should have announced that he was suspending his journalistic career with immediate effect the weekend after the referendum result. What was tolerated when he was mayor of London was never going to be tolerated by watching voters during a leadership campaign and premiership, because a different level of seriousness is required to run the country.

Is Boris finished? This story is moving so fast that it is impossible to say whether or not he can hold on to enough of the large body of support he has built among Tory MPs. His team must now hope that the storm of Gove’s shock announcement blows itself out, and that this does not shift too many votes in the parliamentary party. But Theresa May is also zeroing in on Boris, and essentially calling him unserious and not up to the task.

If Boris does lose, ironically a journalist will have been undone by his own newspaper column, and by the words of another journalist, Michael Gove, whose style is less flowery than that of Boris. Gove produced in his statement a killer sentence that will endure: “I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead.”