The Huthis and their allies urged parties "to reach a solution and fill the vacuum" within three days or "the revolutionary leadership" would "take care of the situation of the state".
No measures were specified.
The deadline was set in a statement issued at the end of a three-day meeting in a Sanaa sports hall attended by the party of ousted president Ali Abdullah Saleh but boycotted by Yemen's other major political movements.
The militia, which overran Sanaa in September, seized the presidential palace and key government buildings on January 20, plunging the country deeper into crisis and prompting President Abedrabbo Mansour Hadi and his premier to tender their resignations.
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Opponents have staged demonstrations against the Huthis in several cities under the slogan: "Revolt until the overthrow of the coup" forces.
UN envoy Jamel Benomar has said that Hadi and his cabinet are effectively under house arrest, warning that violence could erupt at any time.