It was a debate unlike any other in american presidential history. in fact, it was not much of a debate at all, with president donald trump coming out of the starting blocks intending to talk over anyone else on stage, including democratic rival joe biden and moderator chris wallace. it went downhill from there.

Ft columnists rana foroohar and edward luce, who hosted an online watch-along during the 90-minute debate, called it toxic and an assault on the senses. here are their five takeaways from the first trump-biden duel:

It was clear from the outset that mr trumps preferred tactic was to speak over mr biden despite debate rules that gave each candidate two minutes of uninterrupted time to present their positions.

Mr biden appeared initially shaken by the bulldozing, which mr wallace struggled to restrain, but he was able to regain most of his footing after the initial assault, and he may have delivered the debates most memorable line: would you shut up, man? this is so unpresidential.

Ed argued that mr trumps aggressive tactics were a sign of his desperation and showed that the president was very rattled. the recent revelations in the new york times that he paid little or no federal tax, even while in the white house, was a big blow to his campaign, ed noted. the presidents poll deficit, which has been pretty stable for almost six months, shows no signs of narrowing with only five weeks until election day.

There were times when mr biden appeared on the verge of one of his gaffes. he would not disavow calls to enlarge the supreme court and pack it with democratic nominees, he could not come up with the name of a law enforcement group that endorsed him, and he struggled to explain why he had not contacted democratic leaders in cities that have seen the most violent unrest.

But mr trump stepped on those moments by talking over them, and mr biden was able to use the interruptions to recover, demonstrating he could go toe-to-toe with mr trump despite predictions by the trump team that the former us vice-presidents faculties have been diminished by age.

Mr biden also had some effective moments, especially in spelling out mr trumps failures to tackle the coronavirus pandemic and in what both ed and rana felt was his cleanest win during the final discussion over electoral legitimacy, when he simply but effectively called on americans to turn out to vote, and called for every vote to be counted.

Importantly, mr biden was able to play the happy warrior, smiling and laughing at some of mr trumps most aggressive attacks.

In what may become the debates most controversial moment, mr trump failed to denounce white supremacists when asked about rightwing violence by mr wallace.

Mr biden stepped in to suggest he disavow the proud boys, a far-right group that openly advocates violence and has recently appeared to counter-protest in several us cities. mr trump responded: the proud boys? stand back and stand by.

Mr trump also refused to back down on his contention that the election process is fatally flawed, insisting without evidence that postal voting would lead to widespread fraud. he exaggerated or misconstrued some recent, minor incidents to imply that trump votes were already being illicitly discarded.

As ed argued, the most important line of the debate was one that mr trump did not utter: i will abide by the results of the election, even if i lose.

Rana bluntly suggested that mr biden should pull out of future debates given mr trumps refusal to play by the rules. she argued that a debate like the one on tuesday is not telling voters anything they do not already know. its not helping democracy, and it was just an assault on the senses, she said. nobody won this, we all lost.

Ed was more circumspect. although he found the suggestion intriguing, and noted that mr trump needs the debates more than mr biden who, as the frontrunner has no interest in another mud fight he did not endorse a plan for mr biden to skip the debates.

Thus far, mr bidens surrogates have suggested he is willing to show up at the two remaining debates with mr trump.

With most polls showing mr trump 6-8 points behind mr biden nationally, the president needed a game-changing debate to shift the narrative. although his highly aggressive performance may not cost him anything his over-the-top behaviour has failed to undermine much of his support up to now it is unlikely to win back the constituencies he needs for re-election.

Working-class women, moderate republicans in the suburbs and independents who have backed mr trump for his economic policies despite their concern about his character are unlikely to be regained by the angry outbursts.

Unlike his debate appearances four years ago, when he delivered strong policy lines about limiting immigration, bringing back manufacturing jobs and upending the washington status quo, mr trump failed to present coherent positions.

His attacks ranged from questions about mr bidens son to a rehashing of the controversies surrounding russian interference in the 2016 election attack lines that have failed to win back critical constituencies in the past.