Preaching against the scourges of political correctness and the mainstream media, conservative talk radio has influenced, and reflected, the Republican electorate for a quarter-century. But in a presidential campaign headlined by Donald Trump, the role of talk radio in American politics is more evident in this election than perhaps any other.

Front-runner Trump and his Republican rivals talk more and more like what goes out over the airwaves every day from the likes of talk radio poobah Rush Limbaugh.

"Political correctness is censorship," Limbaugh recently said. 

At a debate, asked why he calls women names like “fat pigs,” Trump responded: "I think the big problem this country has is being political correct."

Here’s Limbaugh, talking about the mainstream media: "The mask is off. The camouflage is gone. The media is the Democrat party."

And here’s candidate Ted Cruz, at another presidential debate: "The questions that have been asked so far in this debate illustrate why the American people don’t trust the media."

These parallels left me wondering whether conservative radio hosts like Limbaugh have helped to create grassroots support for the New York billionaire -- or whether Trump is just a product of what the grassroots have long been griping about.

So I paid a visit to 1210 WPHT in Philadelphia, which airs Limbaugh and other conservatives, to sit in for the afternoon drive-time show hosted by my friend, Rich Zeoli. He opened the program with me at his side.

"You and I had lunch today and one of the questions you asked me is do I drive opinion on this program or do I reflect opinion," he told listeners. "That’s a great question."

Before Zeoli took a call, he offered up an answer. "We don’t tell you what to think about things in talk radio. We don’t. You make up your own minds. You decide for yourself," he said.

Callers to Zeoli’s show told me that unlike liberals, conservatives have a wide variety of views on the issues. 

"We tend to be more open minded and thoughtful, shall we say," said Tony from South Jersey. "I don’t know if we’re necessarily more intelligent, that’s probably not accurate."

Zeoli then chimed in. "In other words I can disagree with you or something and you could still listen to the show, I’m not gonna be dead to you if you have a different position," he said.

"Exactly right," the caller replied.

Even though Trump is not always consistently conservative, Zeoli steers away from any criticism. Otherwise, the show would be flooded with Trump callers and he wouldn't be able to talk about anything else.

"They either love him or hate him," Zeoli said during a commercial break. "There’s no gray area here. It’s the most passionate support I’ve ever ever seen for a candidate in my life."

Radio hosts, though, didn’t create Trump, Zeoli said. "I’ve never once had anyone call up and defend Jeb Bush. Never. What does that tell you about the supposed one-time Republican front runner?"

One possible explanation: Trump, like Zeoli and Limbaugh, all do something that Bush apparently does not: Entertain.

"We’re not trying to do an agenda here. I know that’s what people say but we’re really not," Zeoli said. "We’re trying to entertain people. Political entertainment. Think of it as The Daily Show for the right. "