WASHINGTON  President Obama’s decision to stop short, at least for now, of calling for Hosni Mubarak’s resignation was driven by the administration’s concern that it could lose all leverage over the Egyptian president, and because it feared creating a power vacuum inside the country, according to administration officials involved in the debate.

In recounting Saturday’s deliberations, they said Mr. Obama was acutely conscious of avoiding any perception that the United States was once again quietly engineering the ouster of a major Middle East leader.

But after the president and his advisers met early Saturday afternoon in the Situation Room, Mr. Obama, through a description of the session issued by the National Security Council, once again urged Mr. Mubarak to refrain from violence against the protesters and to support “concrete steps” that advanced political reform within Egypt. He did not define what those steps should be or whether the White House believed they could take place while Mr. Mubarak was in office.

According to senior administration officials at the meeting, Mr. Obama warned that any overt effort by the United States to insert itself into easing Mr. Mubarak out, or easing a successor in, could backfire. “He said several times that the outcome has to be decided by the Egyptian people, and the U.S. cannot be in a position of dictating events,” said a senior administration official, who like others, would not speak for attribution because of the delicacy of the discussions.