In the United States and as well in all countries of the world, the problem is in the qualities of voters . Namely, in universal suffrage. Since the majority of citizens are not competent in politics, economics, poorly versed in the personal qualities of politicians, and do not have ability to political distinguish. Thow, they elect most of the worst politicians, with poor moral qualities and low intelligence. Including those politicians who are prone to lies and have complete incompetence in public administration.
Whereas for the reason that political parties depend on incompetent voters, they are prone to populism and make deliberately wrong decisions (for example, support for Trump) that are imposed on them by the majority of their incompetent voters. In view of which, the tail wags the dog.
This was manifested, for example, in the fact that the Republican Party supports Trump contrary to the interests of the United States, since it is supported by the majority of voters of the Republican Party. The situation is similar with the Democratic Party and other parties. All of them are dependent on their incompetent voters.
The way out of this situation is the abolition of the general suffrage, and the transfer of control power over the state and suffrage to the civilized part of US civil society, selected on the basis of a certain qualification that does not allow incompetent people to become voters or members of the control power. If you make the appropriate amendments to the US Constitution, political parties will already be dependent not on incompetent voters, but on completely competent people who will never vote for politicians like Trump, and the like.
In view of what, the US political system will get rid of populism and move on to a sustainable existence. That is, to such an existence as if all voters under universal suffrage would be fully competent people.