Still, a number of major stations said they are meeting or surpassing their fundraising goals in the wake of the furor over Williams' dismissal for saying he gets nervous on a plane when he sees Muslims.
"We find ourselves kind of caught between NPR and the audience," said Craig Curtis, program director at KPCC in Pasadena, Calif., which won't hold its pledge drive until next month. He said the station had received about 150 comments on the firing, mostly disapproving, and three people asked to cancel their memberships.
Meanwhile, conservative leaders including Sarah Palin are calling on Congress to cut off NPR's federal funding - an idea that was also raised in the 1990s and didn't get very far.
Williams was fired Wednesday over comments he made on "The O'Reilly Factor" on the Fox News Channel, his other employer. "When I get on a plane," he said, "I got to tell you, if I see people who are in Muslim garb and I think, you know, they are identifying themselves first and foremost as Muslims, I get worried. I get nervous."
On Friday, Williams said on ABC's "Good Morning America" that NPR had been "looking for a reason to get rid of me" for some time because its executives disapproved of his appearances on Fox.
"They were uncomfortable with the idea that I was talking to the likes of Bill O'Reilly or Sean Hannity," Williams said.
Veronica Richardson, 38, a paralegal from Raleigh, N.C., said the firing revealed that NPR had a "political agenda." She said she would stop listening and donating to her local station, WUNC-FM in Chapel Hill.
"I think it's unfair to fire someone for a comment that was innocuous to begin with. It's how many people feel," said Richardson, who describes herself as a libertarian.
Teresa Kopec, 42, of Spartanburg, S.C., backed the firing, saying, "I thought what he said was kind of offensive. I think it was probably the last straw. He had a pattern of saying things that were not appropriate." But she said his association with conservative Fox News may have been more troubling, because it damaged NPR's reputation for objectivity.
At KUNC, an NPR affiliate in Colorado, general manager Neil Best said that Thursday, the start of a pledge drive, was one of the station's best fundraising days ever. Best said some callers who criticized the firing seemed to be reading from a script since they used some of the same words, such as "totalitarian."
NPR spokeswoman Dana Davis Rehm in Washington said several other stations also reported callers may be reading from a script. In other cases, it was clear the callers weren't listeners or supporters, she said.
"When people say, `I'm never going to watch you again,' that's an indicator," she said, because NPR isn't on TV.
Stations in some big cities such as New York, Washington and Philadelphia, all three of which have been holding pledge drives, said fundraising remained strong even as complaints rolled in. In Denver, Colorado Public Radio President Max Wycisk said the episode could boost fundraising.
"It might actually help, because it reinforces how seriously public radio takes its integrity," Wycisk said.
At least one station wants to distance itself from the firing. In Miami, WLRN general manager John Labonia said he was hearing dozens of complaints from angry citizens and loyal donors. He said one called to cancel a $1,000 pledge. The station's fundraising drive had already ended when the furor erupted.
"We don't want that negative halo of NPR's decision to affect us, so we are making it perfectly clear that we were not part of this decision and we do not agree with it," Labonia said. "It was a short-sighted and irresponsible decision by NPR."
Sen. Jim DeMint, R-S.C., said he will introduce legislation to end federal funding for public radio and television.
"Once again, we find the only free speech liberals support is the speech with which they agree," he said in a statement. "With record debt and unemployment, there's simply no reason to force taxpayers to subsidize a liberal programming they disagree with."
In June, Rep. Doug Lamborn, R-Colo., introduced similar legislation in the House. He said the Williams firing will help his bill.
NPR radio stations are independently owned and operated and, like the nation's public TV stations, receive government funding through the Corporation for Public Broadcasting, which got about $420 million this year from Washington.
As for NPR's headquarters operation, federal grants account for less than 2 percent - or $3.3 million - of its $166 million annual budget. It is funded primarily by its affiliates, corporate sponsors and major donors.
This isn't the first time public broadcasting has been in the crosshairs of conservative politicians. In 1994, then-House Speaker Newt Gingrich called for an end to all federal funding for public broadcasters.
In a statement, Patricia Harrison, president and CEO of the Corporation for Public Broadcasting and a former co-chair of the Republican National Committee, said federal law gives public broadcasting stations "maximum freedom" from interference in their activities.
NPR's Rehm warned that if Congress cut off funding, "stations across the country would be hurt by that and would have to make up that balance elsewhere. In many places that would be difficult to do."
She said that threats to cut off funding are "inappropriate" but that NPR takes them seriously and is talking with its member stations. "Stations as a whole are not happy this is happening at this time," she said. "They're in a difficult situation."
Associated Press Writers Dan Elliott in Denver, Jeff Wilson in Los Angeles, Ben Nuckols in Baltimore, Suzette Laboy in Miami, Kendal Weaver in Birmingham, Ala., Ula Ilnytzky in New York City and JoAnn Loviglio in Philadelphia contributed to this report.