Representatives Lynn Woolsey and Mike Thompson are siding with Sonoma County against federal recognition for Alexander Valley's Wappo Indians, arguing the Interior Department has no power to restore the Wappos' tribal status.

The two members of Congress said they fear the tribe will open a new Indian casino in Sonoma or Napa counties, endangering world-class vineyards.

"The stakes in this matter not only raise constitutional issues ... but serve to threaten the fundamental basis of the region's economy," they said in a letter last month to Interior Secretary Kenneth Salazar.

The letter also was signed by Rep. Don Young of Alaska, who heads the House subcommittee on Indian affairs.

Wappo chairman Scott Gabaldon on Monday called the letter a political move to block his tribe's fight for justice in U.S. District Court. It won't succeed, he said.

"I don't think it will affect the lawsuit," he said. "They are blowing everything out of proportion."

The Wappos have no plans for gaming, but they would get the right to open a casino if their lawsuit is successful, he acknowledged.

"We can't decide anything until we get our federal status," Gabaldon said.

The tribe sued the Interior Department in 2009, charging the government acted unlawfully when it disbanded the tribe in 1959. The Bureau of Indian Affairs established a 54-acre reservation for the Wappos in Sonoma County starting in 1908.

Known as Alexander Valley Rancheria, it was located on the Russian River northeast of Healdsburg. But the tribe lost its federal recognition 51 years later when Congress passed a law aimed at privatizing California's small Indian communities.

The Wappos' lawsuit said the reservation land was improperly distributed and the government didn't keep promises to improve water, roads and sanitation.

They are asking the Interior Department to restore their tribal status, benefits and land rights.

After two years of negotiations, the department is considering a compromise settlement that will recognize the tribe, according to court records.

But Sonoma and Napa counties are against a settlement, saying it would violate their land-use laws. Next month, the counties will ask U.S. District Court Judge Edward Davila to throw out the Wappos' suit.

Woolsey, Thompson and Young support the counties' position, saying the Interior Department has no legal authority to recognize the tribe. Only Congress has power to restore a tribe's status after it has been terminated, they said.

"We believe it is inappropriate for the Department to execute this kind of settlement agreement," the House members said.

A Wappo casino would undermine the area's agriculture protections, they said.

"Napa and Sonoma counties have each gone to extraordinary lengths to protect their agricultural resources and preserve their world-recognized viticulture," they said. "These regulations would not apply to newly acquired tribal lands taken into trust in the region."

Interior Department attorney David Glazer didn't respond to a request for comment, but Gabaldon said recognition of his tribe doesn't affect agriculture.

The Wappos amended their lawsuit to seek only surplus federal land in Sonoma, Napa or Lake counties, he said.