WASHINGTON — Senators have dug in for a prolonged floor fight on health care reform, even after voting on their first two amendments.

While lawmakers approved co-payment–free mammograms and other preventive services for women and rejected a Republican move to eliminate Medicare spending cuts, senators still faced weeks of debate, putting hopes for the passage of the Senate health care reform bill by the year’s end in doubt.

Besides contentiousness between Republicans and Democrats, and between liberal and centrist Democrats, the legislation is running against other priorities. Both the recession and the war in Afghanistan have emerged as pressing concerns before Congress.

State medical associations in Florida, Georgia, Texas and California, meanwhile, have come out against the health reform bill. The California group, which represents 35,000 doctors, said the legislation will raise costs and limit access to care for the poor and the elderly.

In addition, a coalition representing more than 240,000 surgeons has opposed the measure on the grounds that it fails to address Medicare payments to physicians and that it vests too much power in an independent commission that will set Medicare reimbursement rates.

AARP executive vice president Nancy LeaMond said that while the legislation needed work in order to make health care and prescription drugs more affordable for older Americans, “this bill must be strengthened, but it should not be derailed.”

Democratic leaders remained intent on passing the bill this month, even threatening to convene on Christmas Day.

Senate Majority Leader Harry Reid (D., Nev.) said Democrats would do their “very utmost” to approve legislation by the end of the year.

The two parties have traded charges about the bill’s snail’s pace, with Democrats pointing to a letter circulated by Sen. Judd Gregg (R., N.H.) delineating parliamentary moves for stalling progress. Republicans said they want to ensure that the bill is closely examined.

Senate Minority Leader Mitch McConnell (R., Ky.) said the public expected lawmakers to give the legislation all the time that it needed.

The fractiousness within the Democratic party was highlighted when Sen. Ben Nelson (D., Neb.) voted with Republicans in three of four roll call votes early this month.

Majority Whip Dick Durbin (D., Ill.) said a public option and abortion funding remained the two major points of contention among Democrats.

Sen. Mary Landrieu (D., La.), who opposes a government-run insurance plan, said that Democrats were negotiating among themselves because all 60 of their votes were needed “to get this done.”

Democrats said discussions within the party had taken on a new sense of urgency. Sen. Jay Rockefeller (D., W.Va.), a staunch advocate of a public option, called a new initiative on government insurance “highly useful.” He said lawmakers representing various viewpoints would “closet themselves and try and resolve this.”

Sen. Tom Carper (D., Del.), a moderate who favors the public option, was developing a new version of it in collaboration with holdouts, including Nelson, Landrieu and Sen. Blanche Lincoln (D., Ark.).

Various factions are “mindful of the need to pass a solid bill,” Carper said. There was growing recognition that there’s “so much good” in the bill that “we’ve got to find common ground,” he commented.

Among other moderate senators whom Carper met with were Joe Lieberman (I., Conn.), Mark Begich (D., Alaska), Kay Hagan (D., N.C.) and Mark Pryor (D., Ark.). But a division remained apparent.

Lieberman continued to be firmly opposed to any type of public option, saying he felt “strongly about this.” He said he was willing to keep listening but “didn’t hear anything that changes my mind.”

And such liberal senators as Sherrod Brown (D., Ohio) and Bernie Sanders (I., Vt.) expressed an unwillingness to further shift their stances to accommodate centrists.

Brown asserted that liberals had already compromised on government-run insurance three or four times and that the bill would not “continue to become more pro-insurance company. End of story.”