WASHINGTON (AP) — Democrats have made significant progress toward adding compromise provisions curbing prescription drug prices to their massive social and environment package, two congressional aides said Sunday.

Talks were continuing and no final agreement had been reached. But the movement raised hopes that the party's 10-year, $1.75 trillion measure would address the longtime Democratic campaign promise to lower pharmaceutical costs, though more modestly than some wanted.

With talks on that and other issues underway, Democrats were hoping to resolve final differences and bring the overall measure to the floor this week, a House leadership aide said.

The package, carrying President Joe Biden's top domestic priorities, has been a battlefield between progressive and moderate Democrats for months, and it was unclear if that timetable could be met.

According to a senior Democratic aide, under discussion is letting Medicare negotiate lower prices for many pharmaceuticals it provides. Excluded would be drugs for which the Food and Drug Administration has granted initial protection against competition, periods that vary but last several years.

Pharmaceutical makers would have to pay a rebate if their prices rise above certain markers. And there would be a cap on seniors' out-of-pocket drug costs under Medicare Part D, the program's outpatient prescription drug benefit, said the senior aide, who did not provide a figure.

The aides also did not say how much savings the drug price negotiation language under discussion would provide. Recent Democratic proposals that would affect a broader range of drugs had savings estimated at several hundred billion dollars over 10 years.

Party leaders and House Energy and Commerce Committee Chairman Frank Pallone, D-N.J., have been involved in the talks, along with moderates Rep. Scott Peters, D-Calif., and Sen. Kyrsten Sinema, D-Ariz., the senior aide said.

Both aides discussed the talks only on condition of anonymity because they were not authorized to provide the information on the record.

Progressives have also been trying to add provisions including requiring paid family leave and helping millions of immigrants remain in the U.S.

The package would provide large numbers of Americans with assistance to pay for health care, education, raising children and caring for elderly people in their homes. It also would provide tax breaks encouraging cleaner energy and electrified vehicles.

Much of its costs would be covered with higher taxes on people earning over $10 million annually and large corporations.