Isolationalists under Charles Lindbergh, Lillian Gish and Frank Lyod Wright had peaked at 800,000 paying members in 1940. Joseph Kennedy stated that Democracy in Britain was finished, just at it might be in the USA. The isolationists were polling around 40%, but the entire movement collapsed immediately after the Pearl Harbor attack, canceling all meetings and rallies.
Remember that entire Ivy league graduation classes went en-mass to the recruitment centers after Pearl Harbor attack (not to hide in Canada}. The concept that we did not fear Japan because they were not "white" is simply deluded thinking. The House voted 388-1 for war, the Senate 82-0. Food and gas rationing, victory gardens, Civil Defense volunteers, scrap metal drives, War Bonds as Christmas gifts... George Herman Ruth Jr. (Babe) offered to buy $100,000.00 of Bonds (max allowed was $50,000).
This was a reaction against the Empire of Japan, not Germany. Now FDR, who basically became president for life (a separate discussion for sure), concocted the Europe First strategy.
My point is that he would have been forced to change the Europe first strategy had the Empire of Japan made significant gains at Midway and Hawaii (although I agree this was extremely unlikely) .
Now in hindsight, the US public mood appears less virulent versus the Japanese, but I had a girlfriend whose American citizen father of Japanese decent (who owed a butcher shop in LA) was interned and forced to butcher for free. They never even gave him his butcher shop back after he was released.
Midway and Hawaii, Meh, I doubt it.
Rich