The reports seemed increasingly convincing, to both protesters and even high-ranking officials. Hossam Badrawy, the top official of the ruling party, said in a television interview that he had personally told the president he should resign. And, though Mr. Mubarak did not respond, Mr. Badrawy said he believed he would go. “That is my expectation, that is my hope,” he added in an interview. The news electrified protestors in the square. Wael Ghonim, a Google executive and protest organizer whose anti-torture Facebook page helped ignite the movement, celebrated in a Twitter feed: “Mission accomplished. Thanks to all the brave young Egyptians.” The crowd in Tahrir Square soon swelled to half a million.

But as night fell on a rainy day and Egyptians huddled around their televisions in anticipation of a presidential resignation speech, confusion began to swirl. Contradicting what had become a widespread conviction that Mr. Mubarak was on the way out, the minister of information said the president would not resign at all. On state television, agitated analysts speculated openly about conflict between the president and military.

Mr. Mubarak opened his speech with words that suggested he was staying. “I am addressing all of you from the heart, a speech from the father to his sons and daughters,” he said. He expressed what he described as pride for them.

The response ranged from the despondent to the desperate.

“Can this man be serious or did he lose his mind?” asked George Ishak, a longtime opposition leader. “People will not go home and tomorrow will be a horrible day. It is a redundant speech, it is annoying and we heard it a thousand times before.”

Mohamed ElBaradei, an opposition leader and Nobel laureate, was blunter. “I ask the army to intervene immediately to save Egypt,” he wrote on his Twitter feed. “The credibility of the army is being put to the test.”