The United States has a strong history of maintaining boundaries between mainstream politics and extremist ideologies. Throughout the years, both the Democratic and Republican parties have actively challenged and marginalized radical figures within their ranks, preventing them from gaining significant traction or influence in mainstream political discourse. This protective mechanism has helped to preserve democratic norms and stability within the political landscape.

However, this historical gatekeeping faced its most significant test in 2016 when unconventional and extremist elements began to break through these established barriers. The emergence of such figures into the mainstream political narrative marked a pivotal shift in American politics, prompting concerns about the health and integrity of the democratic process, as highlighted by Steven Levitsky in his book "How Democracies Die."