The most popular program among public broadcasters these days may be the Great Funding Commercials.

Faced with impending federal budget cuts, public TV and radio stations around the country have taken to their airwaves to highlight the situation. In ads airing during prime-time hours, the stations are urging viewers to call members of Congress to tell them how they feel about the impending loss of more than $100 million in federal funds for the Public Broadcasting Service, National Public Radio and hundreds of public radio and TV stations.

WETA, Channel 26, began running 30-second spots on Friday, sprinkling them throughout such programs as "The NewsHour With Jim Lehrer," "Washington Week in Review" and "The Charlie Rose Show." The ads direct viewers to the station's Web site, where WETA has assembled a series of "talking points" to use when calling Congress. ("Express to your legislator the impact that public broadcasting has had on your life -- be specific, if possible.")

Similar spots are running on at least 90 of the 175 licensed public TV stations across the country, according to the Association of Public Television Stations, a Washington-based lobbying organization that is coordinating the effort. "Almost all" of the 780 public radio stations affiliated with NPR are posting appeals on their Web sites or airing ads, according to NPR.

The unusual advocacy campaign -- which may be the largest single effort ever mounted by public broadcasters on any issue -- comes at a critical time for the industry. A House committee on Thursday agreed to cut public broadcasters' annual appropriation by 25 percent, or $100 million. It also cut another $78 million in funds earmarked for children's educational TV programming, and satellite and digital transmission improvements. All told, station officials say the cuts amount to a 45 percent reduction in federal funds.

Public stations have been down this road before. Former House speaker Newt Gingrich's threat to "zero out" federal funding for broadcasters in 1995 stirred up a similar, though smaller, ad campaign that succeeded in restoring full funding. In addition to running ads, broadcasters rallied public support then by bringing Big Bird to Capitol Hill for a photo op.

A rally scheduled for today in Washington will feature another PBS kids' star, Clifford the Big Red Dog.

This time, broadcasting officials say they were left with little time, and few choices, to rally public support. "We had a debate in 1995 that lasted for several months before we ever got to a vote," said John Lawson, the president of APTS. "This time we don't have that luxury. We're using the airwaves to inform people about what's happening. We not only have a right to inform our citizens but an obligation to do it. We're not going to play the role of abused spouse and suffer in silence until something awful happens."

But some question the tactics as well as the goals. "There's a feeling from our perspective that there's no equal time to say, 'Here's why we support the cuts,' " said Tim Graham, director of media analysis for the conservative Media Research Council. "We certainly aren't going to see an anti-pledge drive."

Graham says public stations can get along fine without federal support, which amounts to about 15 percent of all the funds the public broadcast industry collects each year. "These stations are massive and very rich," he says. "They got all the resources they want. A cut is not going to mean the end of these stations."

The ads do give pause to some public broadcasting supporters, among them Jeffrey Chester, who heads a Washington organization called the Center for Digital Democracy. Because the stations receive government money, he believes "there needs to be some things off-limits, including the lobbying of Congress and other lawmakers" over the airwaves. "The stations are obviously feeling desperate and are using all the resources at their disposal. But they should be wary about crossing the lobbying line. . . . I would say the stations are making a political mistake using their airwaves to lobby."

WETA's ad dramatizes the station's plight by showing a series of images of popular PBS programs, including "Sesame Street," as a voice-over says, "As you may know, some in Congress have moved to cut federal funding for public broadcasting by 45 percent, and they want to completely eliminate federal funding that supports educational and children's programs. Shows like 'Arthur,' 'Sesame Street' and 'Clifford' are at risk. . . . These cuts would have a devastating effect on WETA and the television and radio programs you and your family enjoy, like 'Masterpiece Theatre,' 'Mystery!,' 'Nova' and 'The NewsHour.' Do your elected officials know how you feel about federal funding for public broadcasting?"

A station spokeswoman, Mary Stewart, said WETA would lose about $1 million directly under the House legislation. The indirect losses could be much greater, she said, because public stations would lose funds that they contribute to WETA to help it produce such national programs as "The NewsHour," "Washington Week in Review" and Ken Burns's documentaries.

WETA had $66.8 million in annual revenue last year, of which $39 million went into producing national programs, and $27.8 million was for operating WETA-TV and WETA-FM.