Looks like we’ll be watching a nail-biter on healthcare, as Senate Dem leaders attempt to come in under the wire Saturday to start a procedural process that will enable them to pass a healthcare bill before Christmas Day. All signs point to them NOT getting a crucial CBO score today on the amendment Majority Leader Harry Reid, D-NV, has been working on (called the “manager’s amendment”) that encompasses all of the changes to his original 2,074-page bill.

We can report that congressional sources tell Fox – Democrats are very happy with CBO’s analysis so far, BUT --- the devil is in the details – everyone is waiting for the details.

The hold up? Sen. Ben Nelson, D-NE, and his abortion language objections, primarily, along with other changes being made to pacify the conservative Democrat. The manager’s amendment is being tweaked, which, in turn, holds up CBO.

 The abortion compromise talks involve Sens. Reid, Barbara Boxer, D-CA, an ardent pro-choice Dem, Chuck Schumer, D-NY, and pro-life Sen. Bob Casey, D-PA, according to a Senate Democratic aide. Looks to be no White House involvement on this topic, according to several participants.

The root of the problem? No one can figure out how to fence off federal money when people enter the state-based healthcare exchanges. Current law, authored by former Cong. Henry Hyde, is virtually impossible to apply, said one Dem aide with knowledge of the negotiations, in reference to current law that bans federal money from being spent on the procedure, except in cases of rape, incest, or endangerment to the life of the mother. But people getting federal healthcare subsidies would enter a new network to purchase healthcare. How do officials ensure federal money is separated?

The House passed an amendment that would ban insurance plans on the exchanges that cover abortion, forcing women to buy rider plans, that do not yet exist, with their own money. But pro-choice senators, including Boxer, have said that language will not fly.

One key source with knowledge of the original “Gang of 6” Finance Committee talks tells Fox that those negotiators were stymied, among several issues, by abortion. It was clear that it would be perhaps the most difficult issue to tackle, according to the source.

Nelson also has other changes he wants, like help for rural hospitals and nursing homes, who, Nelson says, will be hit by the $465 billion Medicare cuts in the Reid bill. One senior Democratic aide tells Fox that, together with the White House and leadership, Nelson should get what he wants on this front.

Nelson’s spokesman sent Fox a statement that simply says, “(Nelson) continues working with colleagues on fiscal issues reducing the cost of health care, on improving the quality of care and ensuring that the federal standard barring public funding of abortion applies to health care legislation under debate in the Senate.”

Reid needs to get all the Nelson changes needed to secure his 60th vote – which enables Reid to shut down a filibuster -- all of the changes into the manager’s amendment by roughly HIGH NOON Saturday, so that Reid can introduce the package and have, per an expected GOP demand, the clerks read the amendment.

That reading is expected to take about 10-11 hours. Reid needs to file a series of procedural motions just before midnight in order to have final passage of healthcare reform by Christmas Eve.

Several senior Democratic sources tell Fox that they remain confident that the impasse with Nelson can be worked out.