If Bloomberg's intervention goes aheadBiden supporters had best brace themselves for disappointment James. My observations of election campaigns in Europe is that big money interventions by high profile billionaires not directly involved in the election tend to hve a negative effect. This has been especially notable in the UK's Bexit referendum.
Though billionaire Arron Banks was one of the main donors to the leave campaign he had also been actively involved in campaigning for Britain to leave for years while financial support from people like Richard Branson and Bod Geldof, though not the biggest sums the campaign reveived attracted adverse publicity and hardened attitudes.
The reaction in pub conversations and internet comment threads could be summed up as, "Who do these rich, spoiled brats think they are, trying to order us about."
You can be sure the Trump campaign is aware of this and will attack appropriately. If Bloomberg truly wanted to help Biden rather than simply embark on another ego trip he wouls have been more subtle.