Of the thousands of complaints that have saturated NPR in the wake of Juan Williams’s firing earlier this week, some of the most telling have been from callers describing themselves as long-time “viewers” of NPR who warn that they are going to “stop watching.”

NPR, of course, does not have viewers, it has listeners. But the public radio organization has come under severe criticism — largely from people who are not listeners, it believes — for having fired Mr. Williams, an analyst who was employed by both NPR and Fox News when he said on Fox that he felt fearful when he saw people in “Muslim garb” on an airplane.

Some have said his comment was bigoted, but others have rallied to Mr. Williams’s defense, and many conservatives have seized on his firing to resurrect their war against public broadcasting.

In an interview on Friday, Vivian Schiller, NPR’s chief executive, defended the decision to dismiss Mr. Williams and said it was not the product of political or financial pressures.