Congressional aides began laying the groundwork Monday for Democratic leaders in the House and Senate to negotiate competing health care reform bills into legislation that can be signed by President Barack Obama, a senior Senate aide confirmed.The Senate on Christmas Eve approved an $871 billion health care reform package on a party-line vote. That legislation must now be merged with a $1.2 trillion health care bill passed by the House before Thanksgiving. Everything happening this week is happening behind the scenes, the Senate aide said of preparations to reconcile the House and Senate bills. Staff is taking the week to review documents. Informal staff meetings may happen, but nothing is scheduled just yet.Senate Finance Chairman Max Baucus (D-Mont.) said just after the Senate approved landmark health care reform legislation Thursday that Congressional leaders would begin holding informal telephone conversations this week on negotiations. The hardest trick for Democrats will be merging the legislation without breaking apart a coalition of 58 Senate Democrats and two Independents.Among the key differences in the two chambers bills: The House legislation includes a public insurance option, while the Senate package does not; the House bill calls for an income surtax on wealthy Americans, while the Senate bill proposes to tax expensive health insurance plans; and the House bill explicitly prohibits federal funds from being used to insure abortion procedures, while the Senate bill allows some flexibility.It remains unclear whether a formal conference committee will be held to resolve those differences. With heavy input from Senate Majority Leader Harry Reid (D-Nev.), Speaker Nancy Pelosi (D-Calif.) and the White House expected regardless, another option is to conduct the negotiations strictly at the leadership level.Senate Democratic leaders said they expect to make a decision in early January on their procedure for reconciling the legislation. That also is when the policy negotiations are expected to begin in earnest. Congress is not set to reconvene from its holiday recess until late next month, but the health care discussions are expected to get under way far in advance of that.Unofficially, Democratic leaders and the White House hope to give Obama a bill to sign in advance of his State of the Union address. Publicly, however, Congressional leaders are refusing to set any deadlines.Im very confident we can get to a finish line here with a bill thats going to survive both the necessary votes in the House and the Senate, Sen. Chris Dodd (D-Conn.), a key health care negotiator, said Thursday.