WASHINGTON — Broadcasters are growing increasingly optimistic about the prospects of a congressional budget proposal that would not only allow them to borrow billions of dollars worth of TV spectrum for free, but would also effectively set no deadline for its return.

House and Senate budget negotiators are resisting the Clinton administration’s efforts to charge broadcasters rent for using a second TV channel to launch a digital TV service.

The Senate is also moving toward language proposed by the House that almost guarantees most TV stations will be able to hold onto their second channels until well beyond the 2006 deadline proposed early this year.

“This is tending well,” said one network lobbyist, adding, “Most Budget and Commerce Committee members oppose fees and support flexibility (for returning the analog channel).”

The administration wants the nation to convert to digital TV by Dec. 31, 2006, so that the analog channels can be reclaimed and sold at auction.

Under the Senate’s latest proposal, the FCC would be given broad authority to extend the deadline on a market-by-market basis. For instance, if any one of the four major networks failed to get a digital TV signal up and running in 2006, the FCC would allow each station in the market to keep its analog channel on the air.

The FCC would also be allowed to extend the deadline if 15% or more of TV households do not subscribe to a multichannel television service providing local digital TV signals.

The bill also would allow broadcasters to keep the analog channels until at least 85% of their market has invested in digital TVs or set-top converter boxes. Although digital TV is expected to be one of the most popular consumer electronics products during the next decade, most industry analysts say it would be a consumer miracle if the penetration rate passed 50% in the next decade.

Follow @Variety on Twitter for breaking news, reviews and more