WASHINGTON -- Democrats worked to smooth the impact of health-care legislation on working-class families yesterday as they pushed President Barack Obama's domestic priority toward a crucial Senate committee vote.

The most far-reaching overhaul in a generation aims to protect millions who have unreliable coverage or none at all and to curb insurance company abuses.

Agreement by the Senate Finance Committee is now all but certain for the legislation, which would bar insurance companies from denying coverage or charging higher premiums on the basis of pre-existing medical conditions. It also includes federal subsidies to make insurance available to millions who lack it, and it takes steps to slow the skyrocketing growth in health-care costs nationwide.

The panel's verdict was sealed after months of private and public struggle, although no final vote is expected until next week. That formality -- Democrats hold a 13-10 committee majority -- will clear the way for the full Senate to begin debating the measure at midmonth.

After days spent largely turning aside Republican calls for changes in the bill, Senate Democrats coalesced behind two changes of their own that could alter the legislation significantly.

One, backed by Sen. Maria Cantwell, D-Wash., would allow states to negotiate with insurers to arrange coverage for people with incomes slightly higher than the cutoff for Medicaid, the government health-care program for the poor. That change was approved.

A second, still pending, would exempt millions from a requirement to purchase insurance, which is currently in the bill. As it stands, individuals and families would be required to buy coverage as long as it cost no more than 10 percent of their income. They would have to pay a penalty if they refused.

The Cantwell proposal is based on a system in Washington state that she said results in lower-cost, high-quality coverage, generally delivered through managed care, as the state uses its purchasing power in negotiations with insurers.

Republicans questioned whether the impact would be to raise insurance premiums for others, and said they were fearful the result would be to reduce health-care options.

Cantwell said the first concern was unfounded, and added Washington has as many as four choices for residents covered by the state program.

The provision passed 12-11 on a near party-line vote.