On Saturday, Williams announced he would vacate the air “for the next several days,” with Lester Holt filling in as anchor of “NBC Nightly News.” Williams is expected to be off for at least a week.

The plan was an effort to buy time for NBC, according to people with knowledge of the situation. The thinking: See if the coverage cools off, find out if there’s other problematic video out there, and see how Holt does. Williams’ Saturday statement includes the key words, “Upon my return” – clearly his hope, although no certainty.

According to the people with knowledge of the situation, the instinct at the top of NBC and Comcast, its corporate parent, has been to try to preserve the asset: Williams is No. 1 at 6:30 p.m. by a wide margin, and “Nightly” is NBC’s only consistently dominant newscast newscast. he sense inside NBC News has been that Williams is too big to fail: He’s just too valuable, and there’s no obvious replacement.