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) Over the next few days, Americans will see two versions of President Donald Trump.

One is the president who will be meeting with North Korean leader Kim Jong Un in Vietnam. The second summit between these two leaders brings with it speculation about a major diplomatic breakthrough that could include a peace deal with a concrete plan for verifiable denuclearization.

The other Trump is the one we'll see when his former fixer Michael Cohen testifies publicly Wednesday before the House Oversight Committee about possible wrongdoing that he alleges the President committed. In a court appearance in December, Cohen said, "time and again, I felt it was my duty to cover up his dirty deeds rather than to listen to my own inner voice and my moral compass." Cohen was sentenced to three years in prison partly for making false statements to Congress, a fact that GOP supporters of the President may use to argue that he is a liar whose testimony cannot be trusted.

This moment of split-screen politics raises the question of whether major progress overseas can save a president from his political problems at home.

Would Trump's ability to broker a durable and verifiable peace deal -- one that has remained elusive to numerous presidents -- to formally end the Korean War, nearly 66 years after an armistice was signed, overshadow the intensifying investigations that his administration faces? Can President Trump pull off the ultimate distraction, not one that revolves around a provocative tweet but instead one that is based on a genuine breakthrough in foreign policy?

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