WASHINGTON (AP) — Democrats sought to limit increases in the cost of insurance sold under a sweeping health care bill Friday as they labored to clear the final committee obstacle to a September showdown on President Barack Obama’s top domestic priority.

Several officials said a last-minute agreement among Democrats on the Energy and Commerce Committee also included authority for the federal government to negotiate directly with pharmaceutical companies for lower drug prices under Medicare.

The changes were part of an intensive effort Democrats have made in recent days to satisfy the conflicting demands of liberals and conservatives on the panel. “We have agreed we need to pull together,” said Rep. Henry Waxman, D-Calif., the committee chairman. He said he hoped for a vote by early evening.

Under a draft amendment in circulation, the cost of insurance to be sold widely under the bill could not rise by more than 1.5 times the annual rate of medical inflation unless the government said otherwise.

The White House declined to state a position on the changes.

Passage in the committee would clear the way for a vote in the full House as early as September on Obama’s drive to remake the face of health care. The pace is far slower than the White House or Democratic leaders had hoped, but still faster than in the Senate.

There, one committee has approved legislation, and bipartisan negotiations in a second panel are scheduled to continue next week as three Republicans and three Democrats reach for a deal.

At their core, all the measures under consideration are designed to achieve Obama’s goal of extending health care to millions who lack it while slowing the growth of medical costs nationwide. Insurance companies would be required to sell coverage to all seeking it, without exclusions for pre-existing medical conditions. The federal government would provide subsidies for lower-income families to help them afford policies that would otherwise be out of their reach.

The bills would set up so-called exchanges, in effect national marketplaces where consumers both with and without subsidies could evaluate different policies and choose the one they wanted.

The main expansion of coverage would not come until 2013 – after the next presidential election.

The House bill also calls for the government to sell insurance in competition with private industry, a hotly contested provision.

A Republican attempt to strip out the government option was turned back on a vote of 31-28, an outcome suggesting that Democrats had a narrow working majority on a committee with 59 members.

A short while later, on a vote that crossed party lines, abortion opponents failed in an attempt to bar insurance plans that offer abortion services from accepting customers with government subsidies. The vote was 31-27.

On Thursday night, the panel agreed on a provision saying the government could neither require nor prohibit abortion services in insurance plans sold in the exchange.

On another heavily lobbied issue, the committee voted 47-11 to grant 12 years of market protection to high-tech drugs used to combat cancer, Parkinson’s and other deadly diseases. The vote was a setback for the White House, which had hoped to give patients faster access to generic versions of costly biotech medicines like the blockbuster cancer drug Avastin.

Rep. Anna Eshoo, D-Calif., said the 12-year timetable would generate $9 billion in savings for the government over a decade.

The political stakes are enormous for Obama and the Democrats as they strive to pass legislation that has proven elusive for years. Republicans are overwhelmingly opposed to the approach they chose, and outside groups on both sides of the issue arranged a heavy dose of television advertising over August.

“Let me assure you: There will be a health care reform bill passed and it will make a big difference in the lives of the American people,” Speaker Nancy Pelosi said in an interview.

But the House Republican Leader, John Boehner of Ohio, countered that “Democrats are in for a long, hot summer once they return to their congressional districts, where Americans are lining up in opposition to a government takeover of health care. ”

Waxman’s announcement of a series of last-minute changes capped a tumultuous period that began more than two weeks ago when conservative and moderate Democrats on the panel sought changes.

Needing their votes, Waxman began negotiations that grew to include Speaker Nancy Pelosi and White House Chief of Staff Rahm Emanuel. An agreement at midweek excluded more businesses from a requirement to offer insurance to their workers and reduced subsidies for lower-income uninsured.

It also swiftly triggered a counter-revolt among liberals, who demanded the subsidies be restored in full.

The final deal accommodated them without sacrificing the concessions made earlier to the conservatives, and included numerous other provisions.

Insurance plans sold in the exchange would need government approval before increasing premiums by more than one and half times medical inflation. The Bureau of Labor Statistics calculated that medical prices rose at an annual rate of 3.6 percent annually for the three months ending in June.

The provision giving the federal government the right to negotiate for better drug prices under Medicare has long been a goal of Democrats who say it could lower costs for seniors. Critics argue that is unlikely unless Congress also limits the drugs than can be sold, thereby giving the government the ability to play one company off against another.

That has long been viewed as politically unfeasible under Medicare, because it would limit the choice that seniors now enjoy.

But including restrictions in the government health insurance option would place it in line with Medicaid, the government program for the poor, as well as the Department of Veterans Affairs and many private plans that limit drug choice.