[U.S. Republican presidential candidate Donald Trump arrives for his campaign rally at the Century Center in South Bend, Indiana, U.S., May 2, 2016. REUTERS/Kamil Krzaczynski]Thomson Reuters Neoconservative columnist Robert Kagan warned in a Washington Post column published Thursday that Donald Trump could be putting America on a path to "fascist" rule. Kagan, a fellow at the Brookings Institution, wrote that the "Republican Party's attempt to treat Donald Trump as a normal political candidate would be laughable were it not so perilous to the republic." "Trump has transcended the party that produced him," Kagan wrote. "His growing army of supporters no longer cares about the party. ... Their allegiance is to him and him alone." Trump is now the presumptive Republican nominee for president. Kagan has previously spoken out against Trump, writing in a previous column that he would vote for Hillary Clinton, the likely Democratic nominee, over the mogul. Trump crushed his more seasoned competitors in state contests, shaking up the traditional political process along the way. Former Florida Gov. Jeb Bush was long thought to be the Republican most likely to win his party's nomination, but he dropped out of the race before winning a single state. Florida Sen. Marco Rubio made it to his home state's primary, but came in a distant second to Trump and then left the race as well. Kagan explained how he believes Trump's unique popular support could lead to fascism: Fascist movements, too, had no coherent ideology, no clear set of prescriptions for what ailed society. 'National socialism' was a bundle of contradictions, united chiefly by what, and who, it opposed; fascism in Italy was anti-liberal, anti-democratic, anti-Marxist, anti-capitalist and anti-clerical. Successful fascism was not about policies but about the strongman, the leader (Il Duce, Der Fuhrer), in whom could be entrusted the fate of the nation. Whatever the problem, he could fix it. Whatever the threat, internal or external, he could vanquish it, and it was unnecessary for him to explain how. Today, there is Putinism, which also has nothing to do with belief or policy but is about the tough man who singlehandedly defends his people against all threats, foreign and domestic. To understand how such movements take over a democracy, one only has to watch the Republican Party today. Kagan argued that Trump doesn't have clear, cohesive policies and plans to fix the problems the US faces. Rather, he offers "an attitude, an aura of crude strength and machismo, a boasting disrespect for the niceties of the democratic culture that he claims, and his followers believe, has produced national weakness and incompetence." READ THE FULL COLUMN AT THE WASHINGTON POST > NOW WATCH: FORMER GREEK FINANCE MINISTER: Why Hillary Clinton is a 'dangerous person'