Washington (CNN) - The Senate launched debate Tuesday on a House-passed bill to make changes in the hours-old health care reform law, with Republicans promising to use every parliamentary tool available to undermine or defeat the measure.
The so-called "fixes" bill was necessary to get reluctant House Democrats to approve the Senate's version of the health care reform bill. By approving the Senate version Sunday night, the House sent the bill to President Obama, who signed it into law on Tuesday.
However, House Democrats only agreed to support the health care bill if the fixes measure accompanied it to make some changes in the Senate version. Now the Senate must approve the fixes bill so Obama also can sign it.
Democrats admit they have concerns that Republicans may be successful in changing the delicately balanced package. Any changes would force the bill back to the House for another vote.