Still, the president's approval rating stands at 56 percent, down from earlier in the year, but strong compared with that of other recent presidents at this point in their first terms, The New York Times/CBS News poll found.
The percentage of people who said they approve of Obama's handling of the war in Afghanistan dropped from 56 percent in April to 44 percent in the new poll. And a majority of Americans say they do not want troops in Afghanistan for more than two years.
Support for Obama's handling of the economy also slipped, from 61 percent in April to 50 percent.
Fifty-five percent said Obama had not clearly explained his plan to overhaul healthcare, and 59 percent said they thought the changes being considered in Congress were confusing, the poll showed.
Still, Americans said they trusted Obama more than Republicans to make the right decisions on healthcare. The poll showed 76 percent said Republicans had not presented a clear healthcare reform plan.
The telephone poll of 1,042 adults was conducted from last Sunday to Wednesday. It has a margin of error of plus or minus 3 percentage points.