■Proponents say AM radio provides critical information in emergencies.

■Study finds that two-thirds of farmers listen to AM radio news.

■Legislation requires U.S. and foreign automakers to equip all vehicles with AM radio.

PORTLAND, Maine — The signal might be fading, but it can’t be lost.

That’s the message from politicians closing in on the votes needed to pass federal legislation requiring AM radio in every new car.

The prevalence of AM broadcast radio has dipped in recent decades as more listeners turn to options such as satellite radio and podcasts during drivetime. But a large, bipartisan group of lawmakers believes saving the AM dial is critical to public safety, especially in rural America, and they want to ensure access to it via car radios.

AM Radio Provides Critical Information

“The emergency alert system works on the AM spectrum — that’s where people get information about emergencies,” said independent Sen. Angus King of Maine. “It’s a critical source of information, particularly in rural areas that might not have clear access to an FM signal.”

King, and Republican Maine Sen. Susan Collins, are among dozens of lawmakers supporting the AM for Every Vehicle Act. Lawmakers first proposed the legislation in the U.S. House of Representatives and U.S. Senate last year, and it has gained a wave of new cosponsors in recent weeks. There are now enough cosponsors to pass the bill in the House, and the Senate is only a few sponsors away, federal records state.

The proposal would have the U.S. Department of Transportation require all new motor vehicles to have devices that can access AM broadcast stations. The rules would apply to vehicles manufactured in the U.S., imported into the country, or shipped in interstate commerce.

Carmakers Dropping the AM Format

The drive to save AM radio comes as some carmakers are phasing the format out. Democratic Sen. Ed Markey of Massachusetts, a proponent of saving AM radio, said last year that he sent a letter to 20 carmakers asking them to maintain AM broadcast and found eight had removed it from electric vehicles.

That is potentially bad news for farming communities and rural parts of the country, lawmakers said. The National Association of Farm Broadcasters found last year that two-thirds of farmers listen to AM radio for news that is important to their operations.

For some farming communities, AM radio “isn’t just another option — it’s the only option,” said Jenni Tilton-Flood, a dairy farmer and owner of Flood Brothers Farm in Clinton, Maine. Even farmers who don’t personally rely on it heavily are aware of that, she said.

It’s unclear when the proposal could come up for votes. The bill was placed on the Senate’s legislative calendar in September.