The U.S. Congress is back in session Tuesday and expected to start the process of merging two very expensive health care plans.

The Senate passed an $871 billion measure on Christmas Eve in a 60-39 vote. That bill must now be combined with a trillion dollar plan passed by the House of Representatives.

On Monday, House and Senate Democrats said they would sidestep traditional procedures in their efforts to negotiate a health care compromise. Such a move would exclude GOP lawmakers, limiting their ability to delay House and Senate votes.

"I look forward to working with members of the House, the Senate and President Obama to reconcile our bills and send the final legislation to the president's desk as soon as possible," House Speaker Nancy Pelosi said late last year as the Senate approved its version of the legislation.

Major concessions were made to both versions, upsetting lawmakers on the left.

Rep. Bart Stupak, D-Mich., says the language in the Senate the bill does not go far enough to prohibit federal funding of abortions.

Both chambers of Congress will most likely meet well into February during the reconciliation process.