The battle over health care is set to reignite this week as Congressional Democrats eye an Easter recess deadline for moving a final reform package to President Barack Obama’s desk and Republicans once again endeavor to erect a bicameral blockade.

Democratic leaders appear close to an agreement on a reconciliation bill, which would act as a companion vehicle of adjustments to the $871 billion health care package that the Senate approved in December. This sidecar legislation, which House Democrats are demanding and is the linchpin of efforts to sidestep a Senate GOP filibuster and clear a final reform bill, also serves as the epicenter of the political fight set to consume Congress.

Democratic leaders expect to obtain a Congressional Budget Office analysis of their reconciliation package by week’s end, after which they would forward the legislation to the Senate Parliamentarian to ensure that it complies with the chamber’s strict rules for 51-vote bills. With Republicans staking their opposition on derailing this package and House Democrats hesitant to support the underlying Senate bill, Obama’s goal of enacting health care reform this year still faces multiple tests.

“I say this as a former House Member, any time you ask the House to swallow a Senate-passed bill, especially on something this broad, it’s a hard thing to ask anybody to do, and we are essentially asking the House to do that,” Sen. Tom Carper (D-Del.) said. “One of the challenges for us is to actually explain to people effectively what’s in the Senate-passed bill.”

House and Senate Democrats in mid-January were on the verge of reconciling the Senate’s health care bill with the $1.2 trillion House package approved before Thanksgiving. But the Jan. 19 election of Sen. Scott Brown (R-Mass.) gave a united Senate Republican Conference the extra seat that it needed to sustain a filibuster, ending the Democrats’ ability to clear a reconciled bill under regular order.

To sidestep this filibuster and sign a final, comprehensive health care bill into law, Obama and Democratic leaders have turned to a rarely used and sometimes controversial procedure known as reconciliation. This Senate tool is designed for budget-related bills and prohibits filibusters, allowing legislation to clear the Senate with only 51 votes instead of facing the usual 60-vote threshold.

The narrow rules governing what policies can be included in a reconciliation bill have created challenges as Democratic leaders attempt to form a bill that passes muster with the Senate Parliamentarian, withstands Republican attempts to defeat it and satisfies Democrats in both chambers. The Democrats’ strategy requires the House to act first — and in fact House Democrats want an ironclad guarantee that Senate Democrats will fulfill their end of the deal.

A senior Democratic Senate aide conceded the difficulties that await the majority if and when a reconciliation bill drops in that chamber, although this individual expressed confidence that Republican obstruction tactics could be overcome. The issue of providing House Democrats with the assurances that they seek also remains outstanding, this aide said.

“It needs to be airtight so there’s nothing the Republicans can do to bring down the whole bill. Our Members are going to have to take a lot of tough votes,” the senior Democratic Senate aide said. “I don’t know what the vehicle is for an assurance. But assurances mean nothing without legislative language.”

As of press time Friday, House and Senate leaders had not sent their reconciliation proposal to the CBO for an official cost estimate, a second senior aide said. Leaders “are still in the process of consulting with Members” on the policy changes in the bill, this aide said. The Obama administration has set a March 18 deadline for the House to act; the Senate hopes to complete its work by March 26, the last day before a scheduled two-week Congressional recess.

Both Republican Congresses and presidents have used reconciliation in the past. But Republicans are crying foul over the Democrats’ use of the procedure in this instance, arguing that it has mostly been used to clear bills that had overwhelming bipartisan support.

Given that Senate Majority Leader Harry Reid (D-Nev.) went through regular order to pass the chamber’s $871 billion health care bill, Republican Senators last week said they felt a certain responsibility during the December debate to avoid going nuclear and bringing the chamber to a screeching halt with unreasonable delays.

But in light of the Democrats’ decision to pursue reconciliation and believing public opinion is with them, Republicans are vowing to do whatever it takes to kill a reconciliation bill. Sen. Orrin Hatch (R-Utah), a Capitol Hill veteran of more than 30 years, said the floor fracas could be among the most intense of his career.

The Republicans’ strategy to defeat the reconciliation bill includes raising numerous budget points of order where they feel the legislation violates the rules and proposing an infinite number of amendments. Unlike a normal bill, Reid cannot prevent Senators from proposing any number of amendments to a reconciliation package.

“It’s certainly going to be a big fight,” Hatch said. “It’s a very improper use of reconciliation.”

But Democrats disagree, contending that using a narrow reconciliation package to enact health care is justified given that the bulk of the overhaul would have been approved in the usual manner and garnered 60 Senate votes. While many Senate Democrats acknowledge that the Republicans might trip them up, others are more optimistic.

“We’ll get it done because it’s such a sense of inevitability,” Senate Finance Chairman Max Baucus (D-Mont.) said. “This is going to pass.”

Emily Pierce contributed to this report.