The deluge of disinformation after the election has hammered home a reality that ought to have been obvious all along: The President is the problem.

Donald Trump did the country the favour of explaining ahead of time how he planned to allege the rigging of the election for his opponent. News networks and platforms alike knew exactly whom and what they would have to deal with. But that doesn't ease the task of stemming the flow of misinformation. Hashtags exhorting readers to "stop the steal" started with a focus on poll-watchers but exploded in popularity after Mr Trump used Twitter to accuse Joe Biden of trying to "STEAL the election," and then took to television to claim baselessly that he had won and that any other outcome would constitute a "fraud".

Purveyors of propaganda within Mr Trump's circle needed no further cues. Eric Trump shared a fake "ballot-burning" video originally from sources affiliated with the QAnon conspiracy theory; he also announced, "We have won Pennsylvania!" even as evidence to the contrary flowed in. Newt Gingrich launched allegations of vote theft on Fox & Friends; Rush Limbaugh shared a viral lie about more votes than registered voters arriving in Wisconsin; hyperpartisan outlets such as One America News declared a second term for the incumbent ("MSM hopes you don't believe your eyes").

Researchers have noted that the fabrications with the furthest reach on social-media sites come from elite influencers, whose followers are so faithful in their resharing that bad actors don't even have to plan their co-ordination any more. Debunked narratives initially spread in one state now reappear in other states that have become key to the election outcome. Phoney stories that were popular weeks ago are revived. There are undoubtedly distortions on the Left, too, such as a misleading tale about the US Postal Service deliberately "losing" 300,000 mail-in ballots — but these gain less traction with no leaders to speed them along.

So, yes, the President and his co-conspirators are the problem. Yet news networks, platforms and other intermediaries to the public must labour to be the solution. Twitter's aggressive labelling of misleading posts coupled with its sharing restrictions have proved fairly effective, although catching those who echo the original falsehoods is tougher. Facebook's label-only strategy has been somewhat less effective but still useful. YouTube has lacked a policy almost entirely. Zeroing in on the downstream superspreaders will prove essential from now on — punishing repeat offenders especially, and taking a tough line on incitements to violence.

Television networks also are struggling with how to handle an unprecedented assault on democracy consisting of patently incorrect but newsworthy claims. Thankfully, anchors have mostly been forceful at pushing back: Fox News's Bret Baier and Martha MacCallum, among others, have set the facts straight on the fanciful fraud accusations. Of course, these efforts would be more effective if their network contended with its own disinformation superspreaders, including Sean Hannity and Laura Ingraham, by challenging their mendacity in something closer to real time.

How to combat dangerous misinformation without impinging on free speech will remain a vexing challenge with no final answer. But the challenge will be almost impossible as long as the most determined purveyor of misinformation is simultaneously the leader of the country.