Personally I think Mearsheimer's thesis makes more sense. The Israel lobby exerts a massive amount of influence over American politics by funding the campaigns of friendly politicians and funding the opponents of those who criticise Israel. This has gradually led to pro-Israel politicians dominating congress, despite the fact that supporting Israel has never been a major campaign issue or a vote winner. Supporting Israel may have been beneficial at times for America's interests but more often than not it has actually damaged them, especially their relationships with oil rich Arab countries in the past. Think about it, what does America get out of unconditionally supporting what Israel is doing right now?
There is literally nothing positive for America doing this, it's damaging America's image in the Arab world and around the world, especially at a time when it's trying to gather more support in the fight against Russia, and it completely undermines it's claim to be standing up for human rights and the oppressed all over the world.
