After less than two years, the Trump presidency is already famous for changing what historians

call traditional norms of America's highest office. Daily tweets were just the beginning.

Now there's Bob Woodward's latest book, The Anonymous New York Times op-ed by an alleged senior

official in Trump's White House, after months of political reporting

denounced by the president himself as fake news. Now, Barack Obama has dramatically changed

another different norm. Former presidents, including Obama's own predecessor, George W. Bush,

have maintained a studied silence about the next

leader and his conduct in office, even when they're from different parties. But in a speech to

students at the University of Illinois, Obama didn't just criticize the policies of the current

administration. He said the president is dividing the country, and he

mentioned his successor by name.

It did not start with Donald Trump. He is a symptom, not the cost.

He's just capitalizing on resentments that politicians have been fanning for years.

Tim Noftali is a presidential historian at New York University.

He's the former director of the Richard Nixon Presidential Library and Museum in Southern California.

Always good to talk to you.

Great time to you, Warren.

My pleasure.

Many Obama supporters are saying it is about time.

Is it? Do you agree with that? President Obama had to make a very

important and historic decision, which is the extent to which he was going to take part in current

political affairs as a former president. He's a, as we know, a very smart man, and he knew that

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