Of most concern to the president himself, one high-level aide said, is the perception that the United States would once again be meddling in the Middle East, where it has overturned many a leader, including Saddam Hussein. Some critics of the United States in the region — as well as some leaders — have already claimed that a Western conspiracy is stoking the revolutions that have overtaken the Middle East.

“He keeps reminding us that the best revolutions are completely organic,” the senior official said, quoting the president.

At the same time, there are persistent voices — in Congress and even inside the administration — arguing that Mr. Obama is moving too slowly. T