The Senate is expected to vote on whether to begin debate -- also known as invoking cloture -- on its version of the health care bill, which was introduced Wednesday by Senate Majority Leader Harry Reid.

The most recent Gallup poll found that 49 percent of the U.S. public approve of the way Obama is doing his job. Most of the decline in Obama's popularity came during the summer, Gallup said, fueled by the long and contentious debate on healthcare and the continued economic slump.

Recent daily tracking polls have shown his approval rating at right around 50 percent.

Gallup surveyed 1,533 people by telephone between Nov. 17 and Nov. 19 as part of its daily tracking. The poll has a margin of error of 4 percent either way.