It was a high-stakes political moment, far from the chummier confines of the “Today” show and, for Matt Lauer, NBC’s stalwart of the morning, a chance to prove his broadcasting mettle on the presidential stage.

The consensus afterward was not kind.

Charged with overseeing a live prime-time forum with Donald J. Trump and Hillary Clinton — widely seen as a dry run of sorts for the coming presidential debates — Mr. Lauer found himself besieged on Wednesday evening by critics of all political stripes, who accused the anchor of unfairness, sloppiness and even sexism in his handling of the event.

Granted 30 minutes with each candidate, who appeared back-to-back at the Intrepid Sea, Air & Space Museum in Manhattan, Mr. Lauer devoted about a third of his time with Mrs. Clinton to questions about her use of a private email server, then seemed to rush through subsequent queries about weighty topics like domestic terror attacks.