Houthi leaders portrayed the plan for a new government as the product of a consensus among Yemen’s political factions. When it was announced, a spokesman, Jamal Asodi, said the new government would be “based on the Constitution,” but he added, “so long as it does not conflict with the revolution.”

Abdul Karim al-Khaiwani, a prominent dissident journalist and Houthi supporter, said that “all walks of life” were represented in the revolutionary committees and that only “one or two” of Yemen’s parties opposed the new plan.

One of those opposed is Islah, an important Sunni Islamist party whose reluctance to agree on a presidential committee with other parties was one of the reason the talks failed Thursday.

The unilateral declaration by the Houthis was also likely to be unpopular in southern Yemen, where separatist sentiment is strong, and in tribal areas where the Yemeni government and the Houthis have tried to win Sunni loyalties away from extremist groups like Al Qaeda in the Arabian Peninsula. Northern and southern Yemen were separate, often antagonistic, countries from 1968 to 1990.

Criticism of the Houthis’ action came quickly on Friday.

“This is a clear coup against democracy and constitutional legitimacy,” said Majid Alshadadi, 35, an education ministry official from Ibb Province. He accused former President Ali Abdullah Saleh, who has allied himself with the Houthis, of being behind the move. “This is the beginning of the end of the Houthis,” he said.