Dr. Abou el-Fotouh “believes in democracy, and he believes in Islam; he accepts liberal values, and he will apply social justice,” said Islam Lotfy, a leader of the Muslim Brotherhood Youth who was among the young instigators of the Egyptian revolution.

“You will find this new trend largely among the youth,” Mr. Lotfy added, “and as you go up the pyramid to people in their 50s and 60s, you will find fewer and fewer.”

“Some in the Brotherhood say he is too liberal,” Mr. Lotfy added, but he argued that those were old-school Islamists who “don’t believe in democracy or some liberal values.”

Older leaders in the Brotherhood, some of whom have clashed with Dr. Abou el-Fotouh for years, are threatening to expel him for defying the group’s pledge not to run a presidential candidate in the first election. The tactic is intended to avoid any appearance of an Islamist takeover — a commitment Dr. Abou el-Fotouh himself laid out on behalf of the Brotherhood in an op-ed in The Washington Post days before Mr. Mubarak resigned. (The date for the presidential elections has not been set.)