Stephen Colbert wishes he could interview Donald Trump again, but he knows that’s never going to happen.

During an appearance on Sirius XM’s The Bill Carter Interview, the Late Show host opened up about the last time he interviewed the Republican presidential nominee and said he doesn’t expect he’ll ever come back on the show.

“I don’t regret the attempt. I regret that that’s probably the only bite I’m going to get at that apple,” he tells former New York Times TV writer Bill Carter. “I would ask him, but it is clear that Donald Trump is a coward ’cause he won’t come back on the show…He’s a chicken.”

When Trump stopped by The Late Show in Sept. 2015, Colbert apologized for some of the mean things he’s said about him over the years and proceeded to ask Trump about his immigration policy. Colbert also asked him if he wanted to apologize for saying President Barack Obama wasn’t born in the United States, but Trump said he wasn’t going to talk about that anymore. (Earlier this month in a press conference, Trump “finished” the birther controversy, saying the president was born in the U.S.)

Read on below for more highlights from the interview, including Colbert’s thoughts on Jimmy Fallon’s highly criticized interview with Trump:

On Fallon’s Donald Trump interview:

“I think the host has this obligation – to be honest with their audience. And you have to go with your honest instincts. My honest instinct is to ask at least one question of some kind of substance with your guest…Every host’s responsibility is to be honest with themselves and with their audience about the kind of show that they do. So I fault no host who acts consistently and honestly. And I know what you’re talking about, but I didn’t actually see it. But I don’t entirely understand the furor about it.”

Colbert also addressed David Letterman wondering why CBS didn’t choose a woman to host The Late Show:

“No, I mean that’s a reasonable question. My guest tonight is Sam Bee on the show. And you know, we’re old friends and we’ve worked together for years, and I think she’s a great choice to host a show. And while it’s not a nightly show, it is a late-night show. And she’s killing it. So there’s no reason not to.”

On why this is a great time to be doing his job:

“It’s the greatest possible time to do topical news because the news landscape is so balkanized that you have to explain a lot to the audience before you can get to the joke, but not the presidential election, especially now…During the general election, everybody cares and nobody gets killed. It’s not a tragic story. Mostly, the stories that everybody knows about are really tragic and you can’t do jokes about it or it takes a long time. It’s very hard to do very quick reaction jokes on stuff that’s sort of nationally known mostly because usually it’s about sadness.”

The entire conversation will air Monday night at 6 p.m. on The Bill Carter Interview (Sirius XM’s Insight channel 121).