WASHINGTON (AP) — House Democrats cleared the way Wednesday for a pivotal floor vote on health care overhaul as early as the weekend, after tweaking their 1,900-page bill to crack down harder on insurance companies.

"Americans are ready for comprehensive health insurance reform and the House will soon act," Speaker Nancy Pelosi, D-Calif., said in a statement that accompanied dozens of last-minute changes to the bill, released Tuesday night.

Publication of the changes started a 72-hour legislative clock, meaning that a floor vote could take place as early as Saturday.

But with no Republican backing for the measure, Democrats will need overwhelming support from their own. A festering intra-party disagreement over how to prevent federal funds from being used to pay for abortion remained unresolved Wednesday morning.

And in the Senate, progress on health care legislation was still on hold.

The 10-year, $1.2 trillion House bill is estimated to expand coverage to about 96 percent of eligible Americans. Beginning in 2013, it would provide government subsidies to extend coverage to tens of millions who now lack it, and ban insurance company practices such as denying coverage to people with pre-existing medical problems.

For the three years before the federal aid starts flowing, the bill would set up a temporary "high-risk pool" through which people who have been denied coverage because of poor health could obtain a government-subsidized policy.

The bill would set up health insurance "exchanges" through which self-employed people and small businesses could buy coverage, either from a private insurer or a new government plan that would compete. All the plans sold through the exchange would have to follow basic consumer protection rules, making it easier to shop and compare among them. The majority of Americans covered under big employer plans would not see dramatic changes.

The House bill would be paid for by boosting taxes on upper income earners and cutting Medicare payments to health insurance companies, hospitals and other medical providers. Democrats also moved Tuesday to close a biofuel tax credit loophole, raising about $23 billion to help pay for the legislation.

The major last-minute changes to the House bill hardened the battle lines in the confrontation between Democrats and the health insurance industry. Insurers have sought above all to block creation of a government insurance plan, which happens to be the top legislative goal for liberals.

Other changes to the bill, such as enhanced status for the government's office of minority health, were intended as sweeteners for supportive lawmakers.

In a move aimed directly at health insurance companies, the revised House bill would launch a federal-state crackdown on what it terms "unjustified premium increases." The companies would have to publicly disclose the justification for premium increases before they go into effect. The federal Health and Human Services department would monitor patterns of premium increases, and could bar insurers from the exchanges if the price hikes are found to be out of line. The bill would also provide $1 billion in grants to state insurance commissioners, allowing them to ramp up their own monitoring and enforcement.

Democrats also strengthened a provision that would strip the industry of its decades-old exemption from federal antitrust laws.

Supporters said the tougher approach is needed to keep insurance companies from artificially boosting premiums in advance of the major reforms taking effect in 2013.

While the White House cheered the momentum in the House, the Senate's top Democrat signaled Tuesday that Congress may fail to meet President Barack Obama's self-imposed year-end deadline for passing health care legislation. That would leave the fate of Obama's top domestic priority to the uncertainties of the 2010 election season.

Majority Leader Harry Reid, D-Nev., spoke as Democratic officials said it could be December before Senate debate begins in earnest. The drive to pass legislation has been plagued for months by divisions within the party's rank and file.

Any delay past Obama's oft-repeated year-end timetable would put the issue off until the 2010 election year and inevitably raise doubts about Democrats' ability to deliver on behalf of the Obama administration.