You can go as far back as Reagan or maybe even Nixon (although the The Heritage Foundation was born due to some people thinking he was too soft), the bucket does not stop at Bush Jr.

The situation fundamentally starts in the 1960s.

The root cause, or primary driver of the situation today is the exit of the Republican Party and the conservative media/political sphere from bipartisan politics and facts.

These two forces are the ones which rotate the flywheel that powers everything else.

Act in a bipartisan manner? Vote against the party lines ? - get primaried.

Cover something that doesn’t match the prevailing narrative ? Is not of utility to the party ? Be ignored.

Have a narrative that sells and can be used, but is absolutely bonkers or inaccurate? Doesnt matter, it’s going to be used.

This force constantly drove the base further and further right, removed any links to facts or reason at scale.

This in turn supports partisanship at all cost politics, and support for policies that have little to do with complex reality but everything to do with preferred narratives.

Trump has a 92% approval rating amongst republicans from a recent Fox Poll.