Egypt's military announced on national television it had stepped in to secure the country and promised protesters calling for President Hosni Mubarak's ouster that all their demands would soon be met. Mubarak planned a speech to the nation Thursday night, raising expectations he would step down or transfer his powers.

Protesters packed in Cairo's central Tahrir Square broke into chants of "We're almost there, we're almost there" and waved V-for-victory signs as more flowed in to join them well after nightfall, bringing their numbers well over 100,000. But euphoria that they were nearing their goal of Mubarak's fall was tempered with worries that a military takeover could scuttle wider demands for true democracy. Many vowed to continue protests.

The developments created confusion over who was calling the shots in Egypt and whether Mubarak and the military were united on the next steps.

The military's moves had some trappings of an outright takeover, perhaps to push Mubarak out for the army to run the country itself in a break with the constitution. But comments by Mubarak's aides and his meetings with the top two figures in his regime — Vice President Omar Suleiman and Prime Minister Ahmed Shafiq — before his speech suggested he may try to carry out a constitutionally allowed half-measure of handing his powers to Suleiman while keeping his title as president.

That step would likely not satisfy protesters, and it was not clear if the military supports such a move. The United States' CIA director Leon Panetta said Mubarak appeared poised to hand over his powers to Suleiman.

State television said Mubarak will speak to the nation Thursday night from his palace in Cairo. Information Minister Anas el-Fiqqi said he would not resign, state TV reported. Prime Minister Ahmed Shafiq insisted Mubarak was still in control, saying "everything is in the hands of President Hosni Mubarak and no decisions have been taken yet."

President Barack Obama said, "We are witnessing history unfold" in Egypt and vowed the United States would continue to support an orderly and genuine transition to democracy. But he and the White House gave no indication if they knew what the next steps would be. The U.S. has close ties to the Egyptian military, which Washington give $1.3 billion a year in aid.