The land sale, introduced by Nevada Republican Jim Gibbons, was included in a $50 billion budget-cutting bill the House narrowly approved last week. It was not in the Senate's $35 billion version of a budget reduction bill.

Next month, House and Senate negotiators will try to reconcile both bills into a final one and some Senate Democrats say they are determined to delete the land sale measure.

"It would result in a deeply troubling outcome," said Sen. Jeff Bingaman, a New Mexico Democrat. He described the House plan as a "fire sale" that would hurt national parks and forests and have "far-reaching negative consequences."

Congress has been scurrying to find new ways to cut spending with the Iraq war and Hurricane Katrina draining the government's coffers. The mining provision would bring in an estimated gross of $426 million in revenue over 10 years, according to the Congressional Budget Office.

Sen. Dianne Feinstein, a California Democrat, said the land sale "could allow claimants to carve out numerous private enclaves within our public lands."

A key issue is whether the bill would allow the sale of 1,000 acres of existing land claims within national parks.

Brian Kennedy, spokesman for the House Resources Committee headed by California Republican Richard Pombo, called that assertion "absolutely, positively, patently false." A section of the bill explicitly bars the sale of land in national parks, national wildlife refuges, and other federal wilderness areas, Kennedy said.

Democrats and environmentalists say the bill language also allows the sale of "existing claims" -- which includes about 1,000 acres of land within a few of national parks. More worrisome is 2 million acres of existing claims located within five miles of national parks, national forests and wildlife refuges throughout the West, they say.

CENTURY-OLD LAW UPDATED

The House legislation dusted off and updated an 1872 mining law, according to supporters.

To help settle the US West, Congress passed the law to make it easy to stake a claim for the purpose of extracting minerals. Those who wanted to own land claims had to take the additional step of "patenting," or buying it, for $2 to $5 per acre.

Some people laid claims to land that was later incorporated into national parks. And not all claim areas became mining sites -- some have sat untouched for a century.

In 1994, the government halted the sale of public lands for mining, which were still selling for $5 an acre or less. The new House bill would permit anyone who had a claim before the ban to patent the land, but pay at least $1,000 an acre.

The Environmental Working Group said federal land bought under the proposed law -- in or out of national parks -- could be resold for a quick profit or used for non-mining purposes.

"Big box (store) developers, condo developers, why wouldn't they? What would stop them?" said Lauren Sucher, a spokeswoman for Environmental Working Group.

Kennedy said costs would prevent such maneuvers.

The bill requires a company to prove that "mineral development" once occurred on a piece of land or to set up operations related to extracting minerals in order to buy the patent. Corporations are not going to spend dollars to create sham mining operations, Kennedy said.

"You're telling me that a real estate company is going to put up all that, go through all that process, risk all of that capital, knowing full well the whole time that for them to flip it for something other than mining would constitute defrauding the federal government?" he said. "That's just dumb."