Two powerful senators are trying to open the airwaves for community radio stations, aiming to erase restrictions that prevent their rollout in urban areas.

Sens. John McCain (R-Ariz.) and Patrick J. Leahy (D-Vt.) introduced a bill yesterday to lift what they call unnecessary measures designed to prevent signal interference with other FM stations.

Known as "low-power FM stations," the tiny community stations usually have a range of about 3.5 miles. Authorized in 2000, the noncommercial stations are designed to serve highly localized communities.

A number are up and running in less-populated areas, including one in Maryland's Calvert County. Nationwide, more than 200 such stations are on the air. If the McCain-Leahy bill is enacted, as many as 1,000 more could be licensed, community-radio advocates estimate.

Low-power advocates have pushed hard to bring the stations into urban, often-poorer areas, saying that is where they are most needed

But their introduction into urban locations -- where the FM band is crowded with commercial frequencies -- is opposed by National Public Radio and the National Association of Broadcasters (NAB), the trade group of commercial radio stations, each of which maintains the low-power signals will interfere with existing FM stations.

At the urging of commercial broadcasters, Congress in 2000 imposed limits on the licensing of low-power stations, which the McCain-Leahy bill would eradicate. "After spending almost two years and over $2 million, an independent study revealed what the [Federal Communications Commission] and community groups have said all along: Low-power FM radio will do no harm to other broadcasters," McCain said in a statement issued yesterday. The study cited by McCain -- a 2003 report on the likelihood of low-power radio interference prepared by Mitre Corp., a nonprofit technical research firm -- concluded community radio stations would not interfere with larger commercial stations. In February, the FCC told Congress no additional interference studies are needed.

The NAB disagrees.

"It is unfortunate Sen. McCain is relying on the deeply flawed Mitre study in supporting the authorization of more low-power FM stations," NAB President Edward O. Fritts said in a written statement. "Local radio listeners should not be subjected to the inevitable interference that would result from shoe-horning more stations onto an already overcrowded radio dial."

More than 3,400 community groups have applied for low-power licenses. Church groups account for about 40 percent of all granted licenses, the largest group of low-power broadcasters, according to the National Federation of Community Broadcasters.