The drop occurred during this week, since Monday's announcement of the tax deal Obama made with Republicans in Congress, the poll found.
The results were based on weekly averages of Gallup Daily tracking, including interviews with Democrats and independents who said they are Democratic-leaning and liberal, and on interviews with more than 3,000 U.S. adults each week, the poll said.
The president's support among liberal Democrats was starting to drop after the Democratic Party took a beating in the midterm elections and before he reached the tax deal. During the period of Oct. 25-31 -- the last full week prior to the midterm elections -- he averaged an 88 percent approval among the group, the poll indicated.
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