"I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States." (Article Two, Section One, Clause Eight:)Let's read that again. Is there any mention of support for the nation of Israel in that oath?
As a matter of geo-political policy, you can make a case for support of Israel. As a matter of inviolable national policy? No. Even less so as a theological obligation. If you base your support of a candidate on some perceived (and likely bogus) lack of zeal in defending the nation of Israel, you need to reread the Constitution.