WASHINGTON — Senator Ben Nelson of Nebraska, one of three wavering Democrats, said Friday that he would vote to start debate on a giant health care bill as Democrats and Republicans squared off over the legislation in advance of its first big test in the Senate.
Senator Ben Nelson, one of three uncommitted Democrats on the giant health care legislation, talking with reporters on Tuesday.
Mr. Nelson’s announcement had the effect of increasing pressure on the two other uncommitted Democrats, Senators Mary L. Landrieu of Louisiana and Blanche Lincoln of Arkansas, who faces a difficult race for re-election next year.
In agreeing to proceed to the bill, Mr. Nelson emphasized that his vote should not be construed as support for the legislation in its current form.
“Throughout my Senate career,” Mr. Nelson said, “I have consistently rejected efforts to obstruct. That’s what the vote on the motion to proceed is all about. It is not for or against the Senate health care bill released Wednesday. It is only to begin debate and an opportunity to make improvements.”
“If you don’t like a bill,” Mr. Nelson asked, “why block your own opportunity to amend it?”
The Senate plans to vote Saturday on whether to take up the legislation, which would remake the nation’s health care system and provide insurance to more than 30 million people, at a cost of $848 billion over 10 years. The House passed a different version of the legislation two weeks ago.
With no immediate prospect of support from Republicans, the Senate Democratic leader, Harry Reid of Nevada, needs backing from all 60 members of his caucus to clear the first hurdle to action on the bill, which embodies President Obama’s top domestic priority.
Democratic leaders expressed confidence they could muster the 60 votes, even as Republicans stepped up the pressure on centrist Democrats.
Senator John McCain, Republican of Arizona, sent an e-mail message on Friday, urging his supporters to call Mr. Nelson and “ask him to vote ‘no’ on government-run health care.”
In the e-mail, Mr. McCain provided telephone numbers for Mr. Nelson’s offices in Washington and Nebraska. Mr. McCain wrote in his role as chairman of a new political action committee, the Country First PAC.
Technically, the vote Saturday will be on whether to limit debate on Mr. Reid’s motion to take up a bill being used as a vehicle for the Senate Democrats’ health care proposals. But both parties see the vote as a crucial test of strength on the legislation itself.
In debate Friday, senators previewed the arguments they will use. Democrats said their bill would guarantee affordable health care for all Americans, slow the growth of insurance premiums, reduce the federal budget deficit and strengthen Medicare.
“It will save lives and it will save money,” said Senator Richard J. Durbin of Illinois, the No. 2 Democrat in the Senate.
Republicans said the bill would increase taxes, cut Medicare and lead to higher premiums for tens of millions of people who already have insurance.
“Why are we trying to do this — pass this 2,000-page bill that the American people oppose — when we ought to be addressing matters that are clearly needed and urgent?” said the Senate Republican leader, Mitch McConnell of Kentucky.
If Democrats prevail on Saturday, the debate on health care could run for several weeks. Senator Charles E. Grassley of Iowa, the senior Republican on the Finance Committee, predicted that the debate would continue into January.
But Senator Tom Harkin, Democrat of Iowa and chairman of the Senate health committee, said he felt sure the effort would overcome the obstacles that have blocked similar legislation for decades.
“This time it’s unstoppable,” Mr. Harkin said. “We’ve come this far, and we are not going to turn back. We are fulfilling a mandate the American people gave to President Obama and the Democratic Party last November.”
As part of his effort to solidify support for the bill, Mr. Reid disclosed Friday that he had accepted a potentially significant change, which would provide additional insurance options to at least a million people who cannot easily afford insurance offered by their employers.
Under the proposal, by Senator Ron Wyden, Democrat of Oregon, the employer’s contribution to health coverage would be converted into a voucher. Workers could use the voucher to shop for coverage on their own, in new government-regulated markets known as insurance exchanges.
“This would empower individuals, expand consumer choice and create a real health care marketplace where there has been none,” Mr. Wyden said.
Mr. Wyden said he would propose amendments to provide similar choices to millions of additional workers who now have a very narrow range of options — just one or two health plans selected by their employers.
Many companies are apprehensive about such changes, saying they would undermine the employer-based system of health insurance, which provides coverage to more than 150 million people.
R. Bruce Josten, executive vice president of the United States Chamber of Commerce, said Mr. Wyden’s proposal could “encourage employees to abandon their employer’s plan.”
Republicans repeatedly asserted that the Democrats’ bill would expand the federal role in health care and lead to a rationing of care.
“As costs escalate, and the amount of money available is insufficient to pay for everything, inevitably, as in other systems like Great Britain, rationing will result,” said Senator Jon Kyl of Arizona, the No. 2 Republican in the Senate. “Delay of care, that’s how it begins. Then denial of care.”
But Senator Debbie Stabenow, Democrat of Michigan, said, “The ultimate in rationing occurs right now when people lose their lives because they cannot find affordable coverage or are arbitrarily dropped by their insurance companies and cannot see a doctor or get the care they need.”
In scheduling the vote on Saturday, Mr. Reid made sure to keep a commitment to Mrs. Lincoln that all senators would have at least 72 hours to study the bill after it was released.
Mr. Reid posted the text of his bill on the Internet on Wednesday night, after a meeting of the Democratic caucus. Aides to Mrs. Lincoln said Friday that she was still studying it.
