Tuesday on CNN’s “Outfront,” CNN contributor David Gergen, a former presidential adviser that served in the Nixon, Ford, Reagan and Clinton administrations, explained why he sides with presumptive Republican presidential nominee Donald Trump on using the term “radical Islam” to describe the terror threat aimed at the United States.

According to Gergen, using such terms provides “clarity,” which he likened to Ronald Reagan describing the Soviet Union as the “evil empire.”

“Absolute disdain for Donald Trump and everything he represents,” Gergen said in describing Obama’s speech earlier in the day. “There’s a great fear on the president’s part that Donald Trump could actually succeed. He’ll do everything in his power from prevent that from happening. I must say on the substance, you have to distinguish between two things – and that is the ban on all Muslims trump is calling for, versus using the term radical Islam. On the first, I think the president is doing very well on that issue. I think he’s got the upper hand on that issue. A lot of Americans … don’t like the ban.”

“They think it was a bad idea. Importantly, high-ranking Republicans very, very important to him right now are opposed to this ban,” he continued. “Paul Ryan has made it repeatedly clear and said so again today and Trump doesn’t want to face a rebellion before the convention among the Congress. On the second point, radical Islam if I may be permitted a quick story. Back in the early 1980s, President Reagan was trying to decide whether to call the Soviet Union an evil empire. I was among those who urged him not to do that on his staff. I thought it was wrong. I thought it would upset the Soviets. I think in retrospect I was wrong. He used the term. I think it worked well. Tony Dolan who was a speechwriter was the one who persuaded him. He had the better argument and that is rhetorically confronting, telling, having plain-spoken truth about what you’re facing helps to clarify and helps to strengthen your hand.”

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