Julian Zelizer studies America’s past, but he plays a big role in its present. A professor of history and public affairs at Princeton University, Zelizer is a frequent commentator and guest on the media and writes a weekly column for CNN.com. He is the author of numerous books about American politicians and the American political system, including studies of the presidencies of Jimmy Carter, Ronald Reagan and, most recently, Lyndon Johnson. Recently, he stopped by the offices of BillMoyers.com for a conversation about this year’s presidential campaign. The transcript has been edited lightly for clarity.

Kathy Kiely: So, has there ever been a campaign like this in American history?

Julian Zelizer: No. Usually when I’m asked that as a historian, I can think of something that was pretty much like the campaign that’s taking place, or closely resembles it. In general, this is pretty distinct — obviously as a result of Donald Trump. I think there’s elements of it that we’ve seen in different ways in the past. In 1968, the third-party candidate was somebody named George Wallace, who was the governor of Alabama, and he appealed to white Democrats to join him, through similar appeals based on race — rather than issues of immigration, for example — that we’ve seen emerge again with Donald Trump in this conservative, populist rhetoric that has been very central to his campaign.

In 1964, you saw Republican Barry Goldwater, who wasn’t considered to really be integral to the party at that point, who was far off-center, and was someone who was going to inevitably lose, in the mind of many Republicans — and so there’s an element of that going on today. But it’s very peculiar mix, given his own background professionally, given the media environment in which he’s really thrived, and given his own style, his own political style, which is really quite different than, I think, anything we’ve seen in mainstream, in the two big parties. ...