WASHINGTON – A California-led proposal to tighten wine-labeling rules has rallied the state's lawmakers, split the industry and spurred a debate that shows no signs of resolution.

Flexing political muscles, 48 members of the House of Representatives, including three dozen Californians, are seeking tighter labeling rules to protect the value of names like "Napa Valley." Opponents fear the consequences, with one Texas winemaker warning that new rules would prove a "devastating blow."

Winemakers, oenophiles and others have until Dec. 7 to opine on the new labeling rules proposed in June. The rules would further restrict how out-of-state producers can use viticultural areas on their labels.

Concerns raised by Texas winemaker Kert Platner, for instance, were echoed by Lodi, Calif., winemaker Dave Pechan, who called the rule changes "absolutely unworkable."

On the flip side, lawmakers from New York and Oregon joined the California House members in urging regulators to act soon.

"A final regulation is needed [to] protect consumers from deceptive labeling practices as well as the integrity of American viticultural areas," the U.S. House Wine Caucus members wrote.

The label rules in question govern appellation of origin and certain other identifying words.

An appellation of origin is a designated and distinctive region, such as the 22,400-acre Edna Valley American Viticultural Area in San Luis Obispo County, Calif.

Federal rules require that at least 85 percent of a wine whose label includes a viticultural area be derived from grapes grown within the designated region. The wine must also be fully produced within the state.

A loophole, though, exempts wines that are sold strictly within single states rather than being placed into interstate commerce.

A wine made in Georgia with Napa Valley grapes, for instance, has been labeled as "Napa Valley," according to Rep. Mike Thompson, a California Democrat.

The rule proposed in June would extend the general interstate labeling requirements to those wines sold within single states.