The House changes, which drew immediate opposition from liberals in the chamber, would reduce the federal subsidies designed to help lower-income families afford insurance, exempt additional businesses from a requirement to offer insurance to their workers and change the terms of a government insurance option.
At their core, both the House bill and the plan under negotiation in the Senate are designed to meet President Barack Obama's goals of spreading health coverage to millions who now lack it, while slowing the skyrocketing growth in health care costs nationally.
Obama has placed the issue atop his domestic agenda, and as recently as two weeks ago was pressing the House and Senate insistently to pass separate bills by the end of July or early August.
The White House issued a statement praising the development in the House, and with appearances in North Carolina and Virginia, the president sought to minimize the significance of the slippage in his timetable.
"We did give them a deadline, and sort of we missed that deadline. But that's OK," Obama said. "We don't want to just do it quickly, we want to do it right."
In his appearances, Obama stressed that any legislation he signs will include numerous consumer protections, including a ban on insurance company denials of coverage based on pre-existing medical conditions.
Rep. Mike Ross of Arkansas, a leader of conservative and moderate "Blue Dog" Democrats, said the changes agreed to by the leadership would cut the cost of the House bill by about $100 billion over 10 years.
While Baucus reported the Senate Finance measure carried a price tag of under $1 trillion, congressional officials said it included only the cost of the first year of a 10-year, $245 billion program to increase doctor fees under Medicare. House Democrats used a similar sleight of hand, excluding the entire $245 billion when claiming their measure wouldn't add to the deficit.
The House deal was worked out over hours of talks that involved not only the chamber's leaders but also White House officials eager to advance the bill. It was unclear, though, what commitments Speaker Nancy Pelosi or the administration may have made to support the agreement once the bill advances to the floor this fall.
As word of the agreement spread, liberals fired back. "We do not support this," said Rep. Lynn Woolsey, D-Calif., head of the Progressive Caucus. "I think they have no idea how many people are against this. They can't possibly be taking us seriously if they're going to bring this forward."
Whatever the longer-term ramifications, Democrats said the way was now clear for the Energy and Commerce Committee to approve its portion of the legislation, the last step before it comes to the floor for a vote.
"We're hoping to get a bill out before we leave ... this week," said Rep. Henry Waxman, D-California, the panel's chairman.
In the Senate, Baucus, Grassley and two other senators from each party have been negotiating for weeks in hopes of agreeing on compromise legislation. Both men face considerable pressure from their respective parties -- Baucus not to stray too far from Democratic objectives, Grassley not to hand the president a political victory.
Majority Leader Harry Reid, D-Nev., has given Baucus months to see compromise across party lines is possible, and he told reporters during the day he expects a bipartisan plan to emerge.
The pace of decisions appears to have accelerated in recent days, with negotiators all but settling on a tax on high-cost insurance plans to help pay for the bill, as well as a new mechanism designed to curtail the growth of Medicare over the next 10 years and beyond.