I don’t see any reason why a particularly isolationist president can’t keep America out. If a president elected in 1940 genuinely wants to keep America out I doubt congress will impeach him to force a war.
Isolationism doesn't mean unilateral disarmament or writing other nations a ticket to do whatever they desire. It just means no interventions in areas where there is no US interest whatsoever.
Once Germany completely overwhelms France, the Lowlands, the Nordics, etc, they have shown themselves a
credible threat to the American SoI. They can make all the protestations that they want about having no interests overseas, but the US was willing to take decisive action very early on to prevent even the possibility of German encroachment (see the American plans to take over the Azores and other potential strategic locations after the Fall of France.
Japan has already started angering the US for years before the fact. The Americans detest the Japanese regardless of any isolation, they see the Japanese as infringing on China unlawfully (and committing atrocities in the process) and rampaging across Southeast Asia, taking European colonies to fuel their own industrialization, and there's only one target that the Japanese would be pointing their industrial base at, as there is only one target that can contain Japan once Britain is distracted by war.
The election is taking place after the fall of France, after the passing of the Two-Ocean Navy Act, the Neutrality patrols initiation, the Japanese Invasion of Indochina, etc. There has been tons of provocation, and while the US is neutral, they most certainly lean towards the British in this regard.
But what if the US exits the Phillipines before the start of WW2?
That does nothing to remove the US's interest in an East Asia that is open to trade as possible. Japan annexing or trying to usurp the Philippines would be taken about as well as Germany doing the same to Cuba in this timeframe; absent nuclear deterrence, there's no reason the US wouldn't step in and forcibly correct the situation.
That's ignoring the fact that even absent US control there would still be American Armed Forces in the Philippines. And note that it was the actions that Japan took in China and later Indochina that drove the US to embargoing Japan, which forced Japan to either desist or try to take out the US fleet at Pearl.
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The best way for the US to never be involved is for no threat to appear to the US - Germany never succeeds in conquering France, the British are freer to keep forces in the East, and the Japanese remain bogged down in China and their economy overheats and crashes and burns eventually.