Julian Zelizer is a professor of history and public affairs at Princeton University and co-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's former personal lawyer Michael Cohen made a series of shocking allegations about the commander in chief Wednesday.

As the President spent his day overseas trying to reach a historic deal with the North Koreans, Cohen painted a portrait of a leader who has engaged in all sorts of fraud, broke campaign finance laws, associated with devious figures, knew of the dirty and possibly illegal tricks being done by some members of his campaign and who instructed associates like Cohen to intimidate people who were perceived as a threat.

As if that was not enough, Cohen alleged that the President is a racist. (All of these allegations have been denied by the White House or by the President's GOP defenders.)

But will the hearings change public opinion?

The Republicans on the Oversight Committee gave a pretty good indication of why President Trump's base is unlikely to move even a little. They essentially are in tune with Trump's statement from 2016: "I could stand in the middle of 5th Avenue and shoot somebody and I wouldn't lose voters."

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