Obviously it will be quite some time before we can fully understand the effect of the attempted assassination on the campaign. But there's little doubt that it's terrible for Democratic chances to hold the WH, principally because it fits perfectly with the race that Trump wanted to run, and decimates the race that Biden wanted to run.

Trump's whole campaign theme is grounded on contrasting a vibrant energetic Trump with a senescent lethargic Biden. They have their issue book to be sure (immigration, inflation, international conflict) - but a core element of their strategy was drawing that contrast. And obviously, his politically perfect response in the few seconds after getting shot just fits that strategy to a T. It turbo-charged that theme.

Meanwhile, Biden's campaign was to portray Trump not merely as a person with bad ideas for the country, but as an individual who was uniquely threatening to democracy. Voters needn't even consider whether they liked Biden or not - all the focus should be on Trump and how terrible he was. And the Democrats would pound, day after day, how terrible Trump was. The debate meltdown had complicated the first part of that strategy, of course - voters were now keenly looking at Biden - but the assassination attempt has crippled the second part of that strategy. If the campaign and its surrogates engage in the same type of rhetoric they were before the shooting, they'll be accused of endangering Trump and encouraging political violence. Every time they bring up January 6th as a catastrophic threat to the Republic, they'll be met with July 13th as an example that political violence isn't only directed at preventing Democrats from taking office, but also at Republicans.

Hence, the vastly improved election odds that hclasvegas mentioned in the other thread. Regardless of the immediate effect on polls and polling, Trump was already winning before the shooting - and this just makes it that much harder for the Democrats to implement their strategy for changing that dynamic.