Nepal's Maoists on Monday said they would agree to a delay of nationwide elections if Nepal is declared a republic.
Elections for a constituent assembly had been scheduled for June 20.
The new legislators are to decide the fate of Nepal's unpopular monarchy.
Speaking to reporters at a Kathmandu hotel Monday, Maoist leader Prachanda appealed for the interim parliament to declare the country a republic.
"If it is not going to happen, if other parties will not agree then there are some other options. The referendum may be another option - a most democratic option," he said. "Even if it is also not agreed then we should have to go among the masses. We shall have to appeal to the masses to rouse again against this feudal system"
A peace deal last year brought the Maoists into the political process after a decade long insurgency that claimed 14,000 lives.
The former rebels agreed to enter the interim coalition government if elections were held in June.
Nepal's election commission says nationwide polling can not take place that soon because of technical and security problems. The government has not set a new election date.
King Gyanendra gave up absolute power last year following demonstrations organized by the political mainstream and the Maoists.
Prachanda on Tuesday rejected speculation that the king would be allowed to remain as a ceremonial figure. He said the position the Maoists once took to allow a constitutional monarch was the biggest mistake they ever made. He said the Maoists have brought the unpopular king to his knees and they will not back off their hard line anti-royalist position.