The Republicans also pledged to move the contentious spending bills early in the year.
Republicans and Democrats have both pledged to restrain or simply abolish the alternative minimum tax.
The Republicans have pledged only to reduce the sales tax by a penny, which would eliminate only $590 million of the $2.8 billion increase.
Both measures, scheduled for votes on Thursday, are among the items that Republicans pledged earlier this month to take up.
Most Republicans, in a turnaround, are distancing themselves from the plan and pledging to protect benefits.
The major Republicans have pledged to win.
Republicans have pledged to bring the bills up for a vote in the first 100 days of the new Congress, which starts in January.
Republicans have pledged to repeal or drastically revise all of them.
The Republicans pledged to change things by assigning to each actor liability for only the portion of the damage he caused.
Most Republicans in Congress have pledged not to raise taxes.