Final answer:
Historians view populism as a political doctrine that supports the rights and powers of the common people in opposition to a perceived elite. Over time, it has taken various forms, from left-wing origins in the US to current concerns over conservative populism, influencing key political reforms and occasionally challenging democratic principles.
Step-by-step explanation:
Historians generally view populism as a political response to concerns about the influence and power held by a perceived elite, reflecting a belief in the rights and power of the common people. In the United States, historically, populist movements emerged with the goal of challenging established interests like nationwide railways and financial policymakers, adopting a left-leaning political stance until the mid-20th century. However, more recent forms of populism, sometimes classified as conservative populism, have raised concerns due to their potential to amplify race-based fears amidst changing demographics.