Most in the news media do not share Mr. Farah and Mr. Corsi’s view. There was distaste evident in the voices of television anchors while they talked about the citizenship issue on Wednesday; the MSNBC anchor Contessa Brewer, reading feedback from viewers, said many were “angry at the media for even covering the Trump birther nonsense.”

At the White House, the NBC correspondent Chuck Todd wondered aloud if Google and its ilk — which enable instant access to all manner of information — cannot be “starved,” then how should the media handle “crazy lies?”…

Only after Mr. Trump spoke out did it become a major topic for the news media. Fox News Channel commentators, who had rarely invoked the issue, started bringing it up, as did their guests; Sean Hannity, Fox’s 9 p.m. host, asked repeatedly in March, “Why can’t they just release the birth certificate?”