I've moderated enough candidates' debates over the years that when I watch a televised debate, I find I often identify with the folks asking the questions.

And I have to say it was painful watching Jim Lehrer at Wednesday night's presidential debate.

I've never met Lehrer, but I've always regarded him with affection. We're fellow Texans, and he wrote a great novel about a working man, a bus driver in Corpus Christi, where I grew up. It's called White Widow, and I recommend it.

Lehrer once described moderating a presidential debate as "walking down the blade of a knife" - how's that for a literary take on a journalistic moment?

But at age 78, it was clear Wednesday night Lehrer had done one debate too many. He mostly watched and asked the candidates to explain their differences.

The shame of it is that Lehrer had the perfect format for one of these things - just two candidates and one journalist with a charge to guide an informed discussion and keep things fair.

I think the best run at this I ever saw was when the Pennsylvania Chamber of Commerce got Tim Russert to moderate a debate in the governor's race. What I loved was that Russert played the candidates' commercials - the attacks they were spending millions to put on voters' TV screens, and made them defend them.

I don't know if Lehrer could have played video or audio, but he certainly could have thoroughly briefed himself on the issues, the candidates' positions and the ads of the campaigns and their super PAC allies, and been prepared to insist on real answers.

As I said I've moderated debates, and while the stakes are different in local elections, the process isn't so much. To do it well, you have to spend a lot of time getting to know the issues and how candidates will try and spin them. Then you have to think on your feet, judging how often to follow up or even interrupt when candidates bluff or filibuster. You want to be the public's advocate and demand the truth, but you don't want to enter the debate.

It's not easy, and for a presidential debate, you need somebody at the top of his or her game. Maybe the Commission on Presidential Debates should have tryouts. Would have saved a great journalist some embarrassment.