American officials said Mr. Panetta was basing his statement not on secret intelligence but on media broadcasts, which began circulating before he sat down before the House Intelligence Committee. But a senior administration official said Mr. Obama had also expected that Egypt was on the cusp of dramatic change. Speaking at Northern Michigan University in Marquette, he said, “We are witnessing history unfold,” adding, “America will do everything we can to support an orderly and genuine transition to democracy.”