Julian Zelizer is a professor of history and public affairs at Princeton University and a New America fellow. He is the author of " Jimmy Carter " and " The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society. " He also is the co-host of the podcast "Politics & Polls." The opinions expressed in this commentary are solely the author's.

(CNN) The President of the United States traffics in conspiracy theories. Donald Trump has brought the art of blaming dark forces for the events taking place in our world to the highest levels of power.

On Saturday, as he confronted the political crisis unfolding as a result of his advisers' contacts with Russian officials -- during the time that the intelligence agencies agree the Russians were systematically intervening in the election -- he found someone else to blame. "How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!" he tweeted.

In another tweet he wrote: "I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to Election!" The source of his accusations perhaps were broadcasts by the conservative talk show hosts Mark Levin and Rush Limbaugh, as well as a story on Breitbart by Joel Pollak. There is no evidence to support the wiretapping claim and Obama's spokesman, along with former members of his administration, have denied it.

Conspiracy theories have always been part of American politics. The historian Richard Hofstadter famously made this a central part of the study of American politics. He best captured this thesis in his 1964 Harper's Magazine article, "The Paranoid Style in American Politics," where he wrote about the ways in which conspiracy theories had been used by various political movements throughout U.S. history.

A historian who was writing in the middle of the McCarthyism of the 1950s and watching the rise of the Radical Right in Republican Barry Goldwater's presidential campaign, Hofstadter was interested in this underside of conservatism. "American politics has often been an arena for angry minds," Hofstadter started his piece by saying. For the "paranoid spokesman," Hofstadter wrote, "The enemy is clearly delineated: he is a perfect model of malice, a kind of amoral superman -- sinister, ubiquitous, powerful, cruel, sensual, luxury-loving."

This is how Trump likes to explain the world. It is not a surprise that he made his political name in 2011 and 2012 by moving to the forefront of the Birther Movement, which falsely argued that President Obama wasn't really American-born. We don't know whether Trump believed in the birther cause or not. And we don't know if he really believes Obama wiretapped him, or whether the President is really as paranoid as he sounds. But what we have seen without question is that he employs the language of conspiracy as a way to make his case to the public.

JUST WATCHED Obama spokesman responds to wiretapping claims Replay More Videos ... MUST WATCH Obama spokesman responds to wiretapping claims 01:20

Trump's entire presidential campaign revolved around several alleged massive conspiracies: "Crooked Hillary," as he called his opponent, had used secret private emails to discuss classified information and hidden her actions from the public. The entire media was "rigged," he said, trying to throw the election to the Democrats even as he enjoyed endless airtime and coverage for his every statement. During the final days of the campaign he turned Bernie Sanders's populist critique -- the way that financial and economic policies hurt the poor -- into an anti-Semitic-tinged campaign ad that showed the faces of some prominent Jewish officials along with a speech about the global economic elite.

Trump continues to use the media as a foil, now blaming them for pouring out "fake news" that covers up every one of his alleged accomplishments -- from the crowd size at his inauguration, to the "real" outcome of the election, to his policy "success" in the First Hundred Days. Trump appointed Michael Flynn to be his National Security Advisor even though Flynn had regularly retweeted all sorts of conspiracy theories that came from crackpot broadcasters and social media contributors.

Trump argued that the press has refused to cover terrorist attacks He hinted of horrors in Sweden that never happened. He has accused refugees of flooding onto the U.S. shores with the intention of conducting massive terrorist attacks against the country.

JUST WATCHED Stelter: Far-right media may fuel Trump claims Replay More Videos ... MUST WATCH Stelter: Far-right media may fuel Trump claims 02:09

He has often picked up on the claims of conspiracy theory guru Alex Jones, a radio host who operates on the fringes of politics. As protesters confront Republican legislators in town hall meetings about ACA, Trump blames the "liberal activists" for being behind the fury. He even told Fox and Friends that President Obama was to blame for the backlash. The President has sometimes given a silent nod to conspiracy theorists, such as when he removed references to Jews on Holocaust Remembrance Day despite the recommendations of the State Department. Doing so played directly into the hands of those who have claimed that the Jewish community somehow invented this massacre against them.

The use of conspiracy by the President of the United States as a central part of his discourse is extraordinarily dangerous. By doing so President Trump gives credence and legitimacy to these kinds of arguments which generate anger and distrust, as well as total misinformation -- in this case making an unfounded accusation against a former president of the United States. Ironically, he is employing a main strategy of McCarthyism at the very time he is claiming to be a victim of those kinds of tactics.

His focus on conspiracy also turns his attention away from the serious political issues that the nation faces. As he capitalized on in the campaign, the middle class is hurting economically and there are serious national security threats confronting the nation and our allies. Yet Trump is so consumed with exposing the "true" stories that are being covered up -- even why former Gov. Arnold Schwarzenegger is leaving "The Apprentice " -- that he is letting the time that Republicans have to accomplish something with united government quickly slip away.

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Over the past couple of weeks, particularly as it relates to Russiagate, there have been more political figures willing to call out Trump and his administration and challenge the way he is performing in office. But it won't be easy to fight his conspiratorial approach. As Hofstadter explained, this kind of rhetoric has deep roots in American history and now there is a President who embraces, rather than pushes back against this tradition, making it challenging for his opponents to engage in rational arguments and to try to win policy debates based on the facts.

Of course, if there was a wiretap the story would probably be even worse for Trump. As the New York Times reported , that would mean that a federal judge had concluded that the Justice Department found enough evidence to believe there was probable cause Trump might be guilty of a major crime or breach of national security.

In a tumultuous world, it is always tempting for people to argue that there are evil forces who are manipulating events. In this case, however, the person who is making those kinds of irresponsible claims is the head of the American government. The President is not speaking truth to the people. And in light of that reality, the health of our democracy is at risk.