The most closely-scrutinised news conference in recent US history got off to a bad start when US President Joe Biden called Kamala Harris "Vice President Trump".
Earlier when introducing the President of Ukraine, Volodymyr Zelensky, at a major public event at the NATO summit he called him President Putin.
But for the vast bulk of the lengthy news conference Mr Biden was in command of the facts and the message - only occasionally straying into long, rambling answers.
He defended his economic record, his considerable legislative achievements, and his foreign policy.
He insisted he was the best-qualified person to govern America and the most likely to best former US President Donald Trump in November's election.
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He also insisted he will not drop out of the race unless his staff tell him he cannot win. But he insisted there is no polling data to support that, and he said he has polls that show he has a clear path to victory.
In the immediate aftermath of the news conference the top Democrat on the House intelligence committee, Congressman Jim Himes, issued a statement calling on Mr Biden to step away from the election, becoming the fifteenth member of the house of representatives to do so. The overall number now stands at 17.
This event - much hyped though it was - has changed little in the Democratic Party’s Presidential crisis: for those in the party who think voters will not buy the idea of Biden being fit to be President when he is 86, nothing in last night’s performance will shift that view.
For those who think he is capable of four more years, they will seize on the President’s capable performance - presenting a compelling record of achievements domestic and foreign.
Though there was not much about what a second Biden administration might bring - heavy on the past and present, the future was conspicuous by its absence in last night’s event.
But for the bulk of the party - especially the Parliamentary party in the House and Senate - those who were on the fence before last night will likely still be there this morning.
Yes, there were gaffes - but if this were any other Biden news conference (of which there have been few) they would hardly merit more than a passing glance from the White House Press corps, and maybe a few social media memes.
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But of course, this was not any other Biden news conference. This was a post-Presidential debate event - and since 27 June all such events see Joe Biden being placed under the microscope - an incredible level of scrutiny that would cause most public figures to wilt.
It is an occupational hazard of all who talk in public for a living that if you speak for long enough you will foul up. It happens to everyone, even the most silver-tongued barristers and sports commentators.
Mr Trump is also subject to this iron law of public speaking - subjecting his verbatim transcripts from his long, rambling rally speeches to the same level of scrutiny as Biden’s produces no end of howlers.
Especially when his autocue breaks and he has to ad-lib.
That’s how we know Trump would rather be electrocuted than eaten by a shark.
Mr Biden’s fate is to find himself falling foul of the public speaking hazard more and more often, at precisely the time he most needs to sound fluent and in command.
For the moment, it is largely a problem of presentation and style: of how he says things, not what he says.
It is also a problem of being elderly and the loss of energy that comes with it.
It happens to different people at different times. Mr Biden is nine months older than Mick Jagger, still touring with the Rolling Stones - but not like he used to.
Mr Trump is 78, older than Ronald Reagan was when he retired. But he still appears a lot more vigorous and energetic than Mr Biden. And that is what a lot of American voters see, someone who speaks and acts forcefully. And they like that.
The words he says less so - but these days it seems what politicians have to say is less highly-prized by the public than how they say those words.
Age catches up with everyone, and at a certain point - a tipping point - people will make a decision: this guy is too old for this job; it’s too demanding, too complex, too tough. It’s just the way it is.
Mr Biden is facing the tipping point.
The decisive move against him is likely to come from members of the US congress who are worried that the Biden effect will pull them all down in November's general election: it’s not just the Presidency that’s on the ballot - lots of federal state and local officials are too, and the Democratic party is reportedly producing internal polling that indicates a bloodbath ahead while Biden is their figurehead.
They have to make their own minds up in the coming days and weeks about what is best - for the country, for the party, but most of all for themselves.
Meanwhile Mr Biden’s campaign continues, taking him today to Michigan, one of the most critical of the must-win states in November’s election. Next week he will be on the road in Texas and Nevada, while Trump hogs the limelight at the Republican Party Convention in Milwaukee - another critical battleground state, which Biden won last time by just over 20,000 votes.
That's about the capacity of the basketball and ice hockey arena the Republican party convention will take place in. In other words, really not much at all.
With such razor-thin margins, it matters if you call Zelensky "Putin".
