CAIRO — The cabinet offered its resignation on Monday to Egypt’s transitional military rulers as security forces carried out an increasingly lethal crackdown on three days of violent street protests, reviving the uncertainty about Egypt’s future that marked the earliest days of the Arab Spring.

Egypt’s military had been seen as the linchpin of the political transition after the ouster of President Hosni Mubarak.

It was the institution Islamists hoped would steer the country to early elections that they were poised to dominate. Liberals regarded it as a hedge against Islamist power. And the Obama administration considered it a partner that it hoped would help secure American interests.

But the cabinet’s offer to resign, in a bow to the protesters’ demands, was the latest blow to the tenuous legitimacy of the ruling military council, just a week before Egypt is scheduled to hold its first parliamentary elections since Mr. Mubarak’s ouster nine months ago.