In the first of a six-part series of interviews with leading historians and political analysts, Martin speaks to the scholar and former Republican adviser Robert Kagan, who has spent a decade warning about Trump's authoritarian ambitions.
They discuss how Trump has accumulated so much power, whether America's democratic institutions can still constrain him, and what might happen if Republicans lose control of Congress.
Could these elections mark a turning point for American democracy or has the country already gone too far down the road towards authoritarianism?
