The venerable Jim Lehrer, who stepped down from the “PBS Newshour” that once bore his name last year after 36 years, returns to television in the biggest way tonight, moderating the highly anticipated first debate of the presidential candidates.

At 78, it will be his 12th time in the high profile duty. But even a decade ago, he told me he was wary of the process.

“They don’t come to debate,” Lehrer said in an interview. “They come to make their statement, because they know there’s a big audience.”

The televised debates, he said, are “The one time they get millions of people watching [and] they want to get their message across… They don’t give a damn what the questions are.'”

For a moderator, “that’s the single most frustrating thing,” Lehrer said, “and the only thing that really annoys me.

“But I think it’s also very revealing. I really do believe the public is picking up on that. I don’t have to tell them.'”

Even if the politicians don’t realize it, he said, “the public is listening, too. You’re not just evading the question of some television person, or some moderator.'”

Moderating a debate is “hard work — the hardest work I’ve ever done,” Lehrer said.

“If I screw up a TV show, I can look at the red light and say I’m sorry. I made a correction last night”,’ he said. “But you screw up a presidential debate — this isn’t a television show, this is an event in the democratic process that leads to the president of the United States. It’s really not a journalism function.

“I would run it very differently if it were running a debate on my program. I’m out there not to introduce new issues, not to press people. If they want to press each other, if they want to harangue each other, that’s fine. But that’s not my job. I just want to make sure that it’s fair.”

And fairness is more than ensuring each candidate has an equal amount of time, he says. “Fairness is where to stop somebody, where to follow up, all those things,” he said. “I’m always very careful to ask apples and apples questions, rather than apples and oranges questions.”

If one candidate is quizzed about character, Lehrer said he makes sure the other gets a similar question.

We’ll see how well he gets to stick to those ideals in tonight’s event.