I do not think that the political system we have in the US makes the US ungovernable. I think what has happened is that corporations along with help from SCOTUS have reached a critical mass of power. They have the majority of the minority party. The Republicans, of course.
The Republicans get their financial support from the US Chamber of Commerce, the Koch Brothers and other super large business entities. The business/large corporation part of the world has the majority of the Republicans in the choke hold of “money rules all.”
The businesses and large corporations feel that they will survive regardless of how irresponsible they act.
Better Answer by BooMan.