A delegation of House Democrats marched unbidden Thursday into closed-door talks over a Medicare (search) prescription drug bill, an act of political theater scripted to dramatize opposition to legislation taking shape in negotiations dominated by Republicans.

Despite the well-mannered intrusion, a core group of negotiators reported progress toward agreement on a bill that would remake the government's 38-year-old program of health care for 40 million Americans age 65 and older and the disabled. "I think we're very close" to a compromise, said Speaker Dennis Hastert (search).

"There are a couple of things that we haven't put to bed yet," the Illinois Republican said, although he added, "I don't know how long its going to take."

Chief among the unresolved issues is a Republican demand for traditional Medicare to compete directly with private plans that would be set up under the legislation.

Also unresolved is a dispute over whether to permit importation of lower-cost prescription drugs from Canada and other countries. Several participants in the talks said senators, citing concerns about the potential for unsafe drugs to enter the United States, appeared unwilling to accept any plan that did not give the FDA veto authority.

New York Rep. Charles Rangel (search) led a dozen or so Democrats into the Capitol office belonging to California Rep. Bill Thomas, site of the House-Senate negotiations dominated by Republicans.

"He believes he doesn't need any Democratic" participation, Rangel said of Thomas, who is chairman of talks designed to put legislation on President Bush's desk by year's end.

While Republicans have declined to permit House Democrats into the talks, Thomas has consulted with lawmakers outside the negotiating room.

He has met at least three times in recent weeks with Sen. Edward M. Kennedy, a liberal from Massachusetts whose support for a Senate bill earlier this year was a turning point in building bipartisan support. Thomas and Kennedy met privately late last week, for example, on the day after Senate Democrats issued a letter sharply criticizing some of the provisions under discussion.

The core group of negotiators -- all but two of them Republicans -- has been meeting for weeks in Thomas' office in the Capitol, systematically working their way through dozens of issues embedded in legislation that would remake Medicare.

Any bill that emerges would create a new prescription drug benefit for older Americans, at the same time it gives private health plans a large new role in the overall health care program, part of an effort to inject competition and hold down future cost increases.

Participants in the talks have said in recent days they are near agreement, although major obstacles remain to be settled.

Chief among them is the Republican demand to have traditional Medicare compete directly with private health plans beginning in 2010. The Bush administration and GOP lawmakers view this proposal as an essential element in their drive to reform Medicare by modernizing it and reining in costs. But Democrats say it could cause the Great Society-era program to unravel by leading to higher premiums for older sicker beneficiaries.

The drug importation issue, another flash point, triggered a massive lobbying campaign by the pharmaceutical industry.

Industry critics pointed to a new study by two researchers at the Boston University School of Public Health estimating that without steps designed to reduce the cost of medication, the legislation would mean dramatically increased profits for drug companies. "This windfall means an estimated $139 billion dollars in increased profits over eight years for the world's most profitable industry," the study concluded.

The House and Senate both approved legislation this year, but the two bills varied in their approach. The House bill was written to appeal to conservatives and passed by a single vote over the vehement opposition of most Democrats. The Senate bill was bipartisan, gaining 76 votes.

With Republicans in control of both houses, the leadership decided to invite only two Senate Democrats, Max Baucus of Montana and John Breaux of Louisiana, to join the group of administration officials and key GOP lawmakers attempting to reach a compromise.

Rangel, the senior Democrat on the House Ways and Means Committee, which is chaired by Thomas, led the delegation that walked uninvited into those discussions during the day.

Emerging later, Rangel protested the decision to exclude him and other House Democrats from the discussions, saying Republicans had made it clear they only wanted to meet with "a group of willing members" of the House.

But, he said, "how could we screw up anything worse that what we read in the paper" about the bill taking shape.