Zelizer is a professor of history and public affairs at Princeton University, and author, with Kevin Kruse, of the new book "Fault Lines: A History of the United States Since 1974." The opinions expressed in this commentary are his own. View more opinion at CNN.

(CNN) President Trump was clearly having a blast during his speech at the Conservative Political Action Conference (CPAC). He soaked up his time in front of the television cameras to offer fans some crowd-pleasers in what was surely a preview of his upcoming presidential campaign. The speech, clocking in at over two hours, was his longest as President.

Julian Zelizer

Going after the Green New Deal, the "sleaze on top" of the FBI and descriptions of the crowd size at his inauguration in 2017, Trump waxed philosophical the way that he does. When he insisted that he was being sarcastic about asking Russia to hack Hillary Clinton's emails, the crowd started chanting their usual refrain of, "Lock her up!"

The conference itself was as interesting and relevant as the speaker. For many decades, CPAC was a meeting place where the right tried to promote its most exciting ideas.

CPAC was created in 1974 by conservatives who believed that they had to do a better job selling their vision to the public after Senator Barry Goldwater's devastating landslide defeat to Lyndon Johnson in 1964. Conservatives were also distraught at what was happening in Richard Nixon's administration and hoped to boost morale given the accelerating investigations into the president's wrongdoing and Vice President Spiro Agnew's disgraceful resignation.

The American Conservative Union, the Young Americans for Freedom and Human Events brought together fellow conservatives in an effort to transform the Republican Party The featured speaker was California Governor Ronald Reagan who invoked Puritan settler John Winthrop when he spoke about the United States and envisioned it as a "city upon a hill."

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