NEW YORK â€"  Former PBS anchor Jim Lehrer says the format of the first presidential debate accomplished its purpose of promoting direct exchanges between the candidates on substantive issues.

Lehrer moderated Wednesday's debate between President Barack Obama and challenger Mitt Romney, who both frequently ignored his efforts to hold them to time limits. He has been criticized on social media for losing control of the debate and not being sharp in his questions.

Lehrer's defenders say there's no shame in letting candidates try to engage each other directly.

A new debate format called for Lehrer to introduce subject areas and give each candidate two minutes to speak, then several more minutes of back-and-forth.

Lehrer says his only frustration was discovering 90 minutes wasn't enough time to cover every issue that deserved attention.