What if isolationist Wendell Willkie was elected instead of FDR for a historical third term? He was quoted as saying he would never send American boys to war, and that FDR "already had them on the transports." If FDR loses, the preparations for war would most likely be lost. No lend-lease, re-armament and gearing up for war manufacturing. The Selective Service Act and Cash and Carry were passed before the election, but who knows if he would have tried to veto them. How would a lack of preparation and isolation mindset have altered the course of the war?
We will never know. I can't imagine that another president would judge Stalin in the same friendly or even naive way, FDR did. "Uncle Joe"... No anti-japanese embargos under Willkie - No Pearl Harbour. Cash&Carry wasn't important, Britain couldn't afford a long war against Germany. Lend&Lease was something different.
Willkie was NOT isolationist. After the election he went to work for FDR and traveled extensively to gather information about the war and communicate with foreign leaders at Roosevelt's request. Elwood, Indiana, has never produced so fine a man since.
For those of you not familiar with the dynamics of the era I will put out a few facts. The "Committee to Defend America First" had about 800,000 members, total, during it's brief existence. That's about 1/2 percent of the population of the US then. How many were active we don't know. The America First and related isolationists in Congress never stopped any measure they were opposed to and never passed any measures they proposed. If Charles Lindbergh hadn't been a spokesman it's somewhat doubtful that they would have gained much notice at all. Both parties had isolationist members in Congress, but most of them were Republicans. A few of the aforesaid members of Congress survived the wartime elections and were on the Congressional Investigation into the Pearl Harbor Attack Committee.
The country was strongly in favor of preparedness, the polls show this. The majority (>60%) were willing to arm our merchantmen even if that meant war with the Axis. More than 68% believed that we would have to fight the Germans and Japanese in the near future. However, in the spirit of the OP, would an isolationist President have killed the national defense programs in place before he took office in March of 1941? No. Even the isolationists believed in defense. The GOP platform for 1940 mentions "defense" eleven times, IIRC. The "non-interventionists" believed in hemispheric defense, or "North of Panama" defense, or "North of the Rio Grande" defense, or "Just us, and devil take the hindmost" defense, depending on who you asked. That was the problem with the isolationists. You had Monroe Doctrine folks and rigid-doctrine Quakers at the same table. They didn't agree on much.
