Senate Republicans turned up the volume against Senate Majority Leader George Mitchell's health reform bill Monday, promising to "use every power" to block it - including a filibuster.

"Anything I can do within the rules of the Senate to prevent the government from taking over or controlling the health care market I'm going to do, and I'm going to do it proudly," Sen. Phil Gramm of Texas said at a joint news conference with Sen. Richard Shelby, D-Ala."If it gets down to the Clinton bill becoming the law of the land, am I willing to use every power that I have as a member of the United States Senate to stop a government takeover of health care? The answer is yes," Gramm said.

The two senators said they would try to strip all taxes from the bill, but Shelby also said ultimately they want to prevent passage of the measure.

"We're trying to stop the bill. We're not trying to balance this bill," he said when asked how the bill's costs for expanding care could be paid without taxes.

Later, asked if he would join a filibuster, Shelby said, "Would I mind filibustering against something like this to kill it? Absolutely not. I would do what I could. But I don't know if that's going to be the strategy," Shelby said.

On the Senate floor, Sen. Arlen Specter, R-Pa., said he was "rethinking" his earlier reluctance to join a potential filibuster. Specter cited the complexity of Mitchell's legislation and the compressed timetable now confronting lawmakers.

Meanwhile, the White House continued its push for universal health coverage.

"As the Congress begins the historic debate, I hope that they and the American people remain focused on what this is all about," said Health and Human Services Secretary Donna Shalala. "This debate is about what kind of lives American people will lead, what kind of future that we'll leave for our children."

The White House considers crucial to passage the bill's reliance on employers and employees sharing the cost of health insurance, and on Sunday two top congressional Democrats insisted there's nothing "radical" in that approach.

"It's not some radical idea to have employers participate with employees in providing health care," House Speaker Tom Foley said on CBS' "Face the Nation." "That's where probably about 60 percent of the American people get their health care now."

"These are not radical plans," House Majority Leader Richard Gephardt said on ABC's "This Week With David Brinkley." "This is building on what we've always done . . . employers and employees share the cost at the place of employment for their health care."

Radical or not, requiring employers to pay a certain proportion of their workers' health insurance - the so-called employer mandate - will be the first key test of health reform in Congress, said White House Chief of Staff Leon Panetta.

"The mandate vote will be the crucial vote with regards to health care," Panetta said on NBC's "Meet the Press." "Right now, it's a tough vote, but we think we can get there. I think we can win this vote."

After a year of public posturing by both sides of the health debate and an unprecedented advertising campaign costing millions of dollars, both houses of Congress take up competing legislation in mid-August.

The Senate will consider the bill promoted by Mitchell, D-Maine, calling for covering 95 percent of Americans by the year 2002. President Clinton has endorsed this plan.