(LATimes) - 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 the new rules would prove a “devastating blow.”

On Thursday, at the request of the Wine Institute and the California Assn. of Winegrape Growers, federal regulators extended a public comment period that's already proved to be revealing despite some distractions within the industry.

“Their members are currently preoccupied with the grape harvest,” the Treasury Department's Alcohol and Tobacco Tax and Trade Bureau noted in explaining the extension.

Winemakers, oenophiles and others now 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.

So far, the 65 comments posted reflect diverse views that aren't always determined by geography.

Concerns raised by Texas winemaker Kert Platner, for instance, were echoed by Lodi, Calif., winemaker Dave Pechan, who called the rule changes “absolutely unworkable.” The California Assn. of Winegrape Growers, requesting more time to study the proposal, warned of lost grape sales.

“Tread carefully when proposed regulations may disrupt long-established commercial relationships,” the association's president, John Aguirre, wrote Aug. 19.

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 Congressional Wine Caucus members wrote Aug. 19.