In 1994, the Republican Party gained control over the House of Representatives for the first time since the 1950s. One key reason for the win was the planned reform of healthcare pushed by president Bill Clinton. After the election, the new Republican caucus would elect Newt Gingrich as it's leader, and he implemented one policy in particular that would have ramifications that continue to this day.
The majority will of the majority party, will determine the actions of the chamber.
For folk like you and me who live in Parliamentary democracies, this seems only natural. This is, after all, a key aspect of how our democracies function. The US, however, had been using a different ruleset for the past 100 years, if not longer. Frequently, the speaker would side with a significant minority of his own party on issues where the majority of the house supported a particular issue. Imagine if you will a 435 member congress where one party has 250 seats, and the other 185. 150 members of the majority oppose a certain bill, while the other 100 support it. Those 100 are backed by the 185 members in the minority. Under the 'old' system, that bill would almost certainly see easy passage. Under the 'new' system developed by Gingrich, roadblocks would be set up to ensure difficulty in passing the legislation. Beyond that, members of the Majority party who voted with such bills would often see their career stall, while members who voted along with the bulk of the majority party would get promoted to committee chair and other such positions.
The key result of this was two fold.
One; it made the party much, much stronger. Now more centrally controlled and organized, the Republicans found winning elections much easier. From 1931 to 1994 the GOP won control over the house for only 4 years. Since 1994, they've been out of power for a short 6 years.
Two; it rapidly increased the radicalization within the party by encouraging its members to stop talking to the other side. This resulted in a GOP that was far more right-wing, far more christian, far more white, far more male, and far more southern than the party had been to that point.
This is where I seemly sharply veer into a poll by yougov about the mob storming of congress. Here is the link: https://today.yougov.com/topics/politics/articles-reports/2021/01/06/US-capitol-trump-poll I encourage everyone to not only check it out, but to click the "table" link near the bottom of the article.
If you do click table, you'll notice that 73% of Republicans honestly think that Trump won the election.
As I see it, there is a direct connection between Gingrich's decision to radicalize the GOP and the fact that 3/4ths of the party now thinks that the election was stolen.
As I see it, the mob storming of congress started on that day in the mid 90s when Newt Gingrich was given control over the Republican Party.