How the police would handle resistance was another question, especially with both sides on edge after the recent deadly clashes. The demonstrators have already erected barricades and stored piles of rocks to throw at attackers. Birdshot pellets and homemade handguns have become increasingly common at Egyptian street protests, including among Islamists. Government officials have accused the Islamists of stockpiling weapons, although both sit-ins appear to be overwhelmingly peaceful.

Brotherhood leaders said Sunday that their demonstrations would remain nonviolent even if the police moved in. Gehad el-Haddad, a Brotherhood spokesman, all but dared them to try. “If they try to disperse the sit-ins by force, we will just create a new sit-in, or multiple sit-ins,” he said. “It is the people who make the sit-ins, not the sit-ins that make the cause.”

For weeks, Mohamed ElBaradei, the interim vice president and Nobel Prize-winning former diplomat — along with a few colleagues, including Ziad Bahaa el-Din, the interim deputy prime minister — had led a push for a patient, less-violent approach to the sit-ins, say human rights advocates and Western diplomats who have worked with the new cabinet. Mr. ElBaradei had urged the new government to seek a political reconciliation with Mr. Morsi’s Islamist backers, the victors in Egypt’s first free elections, that might convince them to participate in a renewed democratic process despite the military takeover.

General Sisi, the central power behind the government, appears to have been persuaded by the arguments for a measured response to the sit-ins, the rights advocates and diplomats said. Among other things, they said, General Sisi may have worried about a possible resignation by Mr. ElBaradei, who has used his international reputation to try to convince the West that Mr. Morsi’s ouster can be a step toward a more inclusive democracy.

But other factions of the government, including the powerful general and military intelligence services, advocated swift and forceful action, the diplomats and rights advocates said. And the tensions within the government had increasingly spilled out into reports by the state-run news organizations and private outlets close to the security services.

Mr. ElBaradei is “dangerous to the people and the state,” a headline in a state-run newspaper recently declared. He is working for the Islamists to “thwart the revolution,” encouraging their “sabotaging” and destructive inclusion in politics, charged a columnist in the state-run newspaper Al Akhbar, laying out an attack still echoing through the privately owned news media as well.