I think making the promise of no americans being sent to die in a foreign war a very powerful campaign promise. Especially when the entire world was being inflamed by it.
Plus, if you really look into FDRs early policies to fight the great depression, one of the first things he did was create the FDIC, and help out the banking industry in order to promote investiment capital and create industrial growth. If he were around today he'd probably get labeled a conservative by todays liberals.
Your really reaching here. Why don't you just admit that FDR would have had a crushing victory over Wilkie no matter what the war issues were?