One of the difficulties with modern politics has been to describe why the US congress has become so unpopular.

The most obvious explanation is that the average age in congress is much older than the general population.

How does this make congress unpopular?

Prejudice people loose the ability to suppress unacceptable behavior as they age. This was acceptable a few generations ago, but has become increasingly unpopular and is now unacceptable to voters.

Modern research is now revealing prejudice to be associated with both lower IQ and mental illness.

Voters find this combination unacceptable.