Ever wondered why Bill O’Reilly rules cable news? Just click on his segment last night with Republican presidential candidate Rick Perry. As O’Reilly had made clear before, Perry’s people were slow to green-light the candidate’s appearance on O’Reilly’s program/hot seat. But given his latest polling numbers, what did he have to lose?

In an extensive discussion last night, O’Reilly struck a phenomenal balance between information/insight and entertainment. In the beginning of the segment, O’Reilly quizzed Perry politely but aggressively on his economic program.

A highlight came in the very beginning, when O’Reilly asked the Texas governor how much revenue the federal government would lose under his newly unveiled economic plan. The question drew a response from Perry that might just interest voters:

“Well, I don’t really worry about what the feds are going to lose.”

After some more economy talk and a discussion about how Perry had botched immigration, O’Reilly was warmed up. It was time to poke and prod, interrupt and cajole — all in service of a delicious story line.

And that was the nearly pugilistic relations between Perry and Mitt Romney. O’Reilly noted that the two would “be hitting each other if assault was legal.” Then he turned to Perry: “There is some strain there, is there not?”

Perry: “I don’t know if there’s strain. There’s certainly a difference of opinion about philosophically where you stand. You can’t change from one election to another.”

O’Reilly: [interrupting to excellent effect] There’s more than that — there’s an edge . . . . You can differ with someone like me, and we’re not going to slug it out. But there, you guys look like you really, ‘Hmmm, don’t like you too much.’ ”

Perry: [Issues a classic, Texas-style three-beat chuckle that appears to be confirming what O’Reilly just said.] “Well, I don’t know about that.”

O’Reilly: [Playful, perfect tone] “You have to know! Come on, what do you mean you don’t know about that? You’re standing there. You like him or not?”

Perry: “You can’t be for banning guns and then all of a sudden for the Second Amendment. You can’t be for the issue of abortion and then you’re pro-life. You can’t be on both sides of these issues.”

O’Reilly: [Showing why the long leash he has at Fox leads to much more compelling interviews than you get on the networks.] “So you think he’s a weasel. You think he’s a weasel. You think he doesn’t have any principles.”

Perry: [Flashes a full-on grin to indicate that he’s really enjoying this dialogue.] “I think in his own words he says, ‘Listen, I need to say whatever I need to say for whatever office I’m running for.’ ”

O’Reilly: “Wow, that’s pretty strong, though. How can you respect a guy — that’s not Texas strong.”