Western officials who have met with General Tohamy and other leaders of the military-led government say he quickly distinguished himself as the most influential advocate of a crackdown.

“He was the most hard-line, the most absolutely unreformed,” one Western diplomat said, speaking on the condition of anonymity to discuss private meetings with General Tohamy. “He talked as if the revolution of 2011 had never even happened.”

General Sisi and the civilian ministers around him initially pledged to try to include Mr. Morsi’s Islamist supporters in a new democratic process. For more than a month, General Sisi appeared to consider the arguments of former Vice President Mohamed ElBaradei and a few others urging restraint in the interest of reconciliation with the Islamists, who had camped out by the tens of thousands at sit-ins protesting the takeover.

But within days of the takeover, General Tohamy was already arguing against any inclusion of the Muslim Brotherhood, the Islamist group that led the voting in elections for Parliament and the presidency. Its members were “terrorists” whose movement must be excluded and crushed, General Tohamy argued, according to the Western officials who met with him and with Egyptians in the new government.