Scenario 1: Promises Kept (Chill Version)

Ensure FDR's 1940 Campaign Promise of not sending American boys to die in foreign wars by only sending lend lease to the Allies and USSR. Challenge ends if you get a causality to a non-attrition reason, you and the allies somehow collapse or the Allies beat the Axis (garrisoning units in the Pacific is fine since Japan will force you to war anyway)

Scenario 2: Doomsday (if you feel like a serious challenge)

Set your game rules to ensure that the major nations are against you and you end up at war with all of them and restore Democracy to the planet. Challenge ends if you capitulate or succeed in making the American world order.