President Mikheil Saakashvili wants to extend lawmakers' terms from four to five years and hold parliamentary and presidential elections simultaneously in early 2009. The president's proposals have angered opposition supporters, who took to the streets in protest early Friday demanding that elections be held in spring 2008.
Georgian opposition leaders have given the government just two hours to review their plans and start dialogue.
"We will give the government until six o'clock to rethink. We have brought over 100,000 people onto the streets, which is the clearest proof that the nation is opposed to official policy," Georgy Khaindrava, a United Opposition leader, told supporters, who have been rallying since 2.00 p.m local time (10:00 a.m. GMT).
A special group of negotiators, including former Georgian Foreign Minister Salome Zurabishvili, and Konstantin Gumtsadze, the leader of the movement For United Georgia, have been sent to talk to the speaker of the country's parliament.
Meanwhile, a group of Georgian opposition supporters are attempting to break through to a government building.
The protesters want to tear down a poster hanging on a ministerial building, depicting a caricature of Badri Patarkatsishvili, a Georgian businessman and opposition leader, but police have so far blocked their path.
Opposition leaders earlier called the poster a provocation.
The presidential press service said earlier in the day that Saakashvili, who himself came to power on the back of a bloodless "rose revolution" in 2003, had no plans to make any statement or meet with the opposition in the next few hours.
