TBILISI, Georgia, Nov. 2 — Tens of thousands of demonstrators converged on the capital of Georgia on Friday, demanding parliamentary elections for early next year and venting dissatisfaction with the country’s once enormously popular government.
The rally, organized by a loose coalition of opposition parties, presented the strongest domestic political challenge thus far to President Mikheil Saakashvili, who rose to office after peaceful protests swept away the country’s post-Soviet old guard four years ago.
Opposition demonstrators filled Rustaveli Avenue, the city’s main boulevard, and packed the entrance to Parliament, where they chanted anti-Saakashvili slogans and issued their demands.
Among them was a call for the government to set parliamentary elections for next spring and enter into negotiations for other power-sharing changes.
Last year, Mr. Saakashvili and Parliament amended the Constitution to extend Parliament’s term to next fall — officially, to align Parliament with the presidential election cycle — an act that the opposition said would make the legislature illegitimate when the term it was elected to expired in the spring.
The demonstration signaled a significant degree of popular discontent with Mr. Saakashvili and his government, which inherited a country in near ruin four years ago and embarked upon an ambitious set of reforms.
Mr. Saakashvili, a lawyer educated at Columbia University, has steered his post-Soviet country sharply toward the West, seeking admission to NATO and the European Union, while moving against corruption at home, especially in the police.
He has often said he hoped to model his country’s development after the experience of the Eastern European countries that were once under the Kremlin’s yoke, and to bring democracy and free markets to the Caucasus, a region with a history of corrupt and autocratic governments.
He has set new standards for education, increased tax collection and revenue-generation, improved the readiness of the country’s once-feeble army and repaired Soviet-era infrastructure to the degree that the country, once plagued by blackouts, now has a reliable electricity supply.
But some of the changes have made him enemies, and he has alienated several prominent politicians, who find him domineering and abrasive. His opponents accuse him of hoarding and abusing power, and of running the nation through a clique that will neither tolerate dissent nor engage in dialogue with the opposition, which Mr. Saakashvili has repeatedly made clear he despises and considers weak.
“The biggest shortcoming for us,” he said in an interview on Wednesday, “is that we failed to grow up a real, mature opposition. The problem with them is that they have no real national leaders.”
The arrest last month of a former defense minister who had criticized Mr. Saakashvili and accused him of crimes also galvanized the opposition. The former minister later recanted on national television and was freed on bail, and left Georgia this week under circumstances still in dispute.
The government insists that the former minister was guilty. But the case has raised questions about whether the police and prosecutors had received political instructions, which the government strongly denies.
The government also faces pressure from rising prices and lingering underemployment, and over complaints about a weak judiciary that many government officials concede lacks independence and that the opposition says remains corrupt. Economic conditions remain difficult enough that many Georgians travel abroad for work.
Western diplomats said their initial estimates had put the crowd at 40,000 to 50,000 people; the opposition claimed to have assembled at least 100,000. Either number rivaled the size of the demonstrations that brought Mr. Saakashvili to power and vastly exceeded the government’s predictions.
The demonstration, held on a day when the government was playing host to foreign diplomats in a conference exploring Georgia’s efforts to integrate with Europe, served as a potential international embarrassment to Mr. Saakashvili, who has been framed abroad as the region’s standard-bearer of democracy.
Mark Lenzi, the local director of the International Republican Institute, an organization affiliated with the Republican Party that promotes democracy, has worked closely with both the opposition and the government. He said the size, energy and timing of the rally showed that political issues and popular grievances had converged and posed the government with a challenge.
“This is definitely a wake-up call,” he said. “It is evident to everyone now that something has to give. There will have to be negotiations between the opposition and the government.”
Although the protests rivaled the size of those, known as the Rose Revolution, that toppled President Eduard Shevardnadze in 2003, most of the opposition leaders said they did not seek another revolution. Even some of the rally’s participants said the opposition had no leader of Mr. Saakashvili’s political stature.
Instead, they said, they sought to demonstrate their strength to Mr. Saakashvili and to persuade him and his government that they must be more inclusive and open to compromise.
“We must struggle by evolution, not by revolutionary means,” Badri Patarkatsishvili, widely regarded as Georgia’s richest man, said by telephone before the rally. “I know my country does not need another revolution. It will not survive it.”
Mr. Patarkatsishvili said late last month he had decided to underwrite the opposition, hoping to balance power in Georgia. Georgian officials have sharply criticized him, saying he is an oligarch with a criminal history, and that he resents the current government because it is honest and will not do his bidding.
“He wants a weak government, destabilized and corrupt, that he can exploit,” said Giga Bokeria, a member of Parliament and one of Mr. Saakashvili’s closest allies. “That is his element, like Yeltsin’s Russia, where he can thrive. We are everything that is against his values.”
Georgia has an active opposition television station, owned by Mr. Patarkatsishvili, and has passed laws ensuring a free press — elements of civil society not evident in many other post-Soviet states. Mr. Bokeria also said that the discontent was a natural leveling of Mr. Saakashvili’s popularity after the revolution, when he won 97 percent of the vote. A decline was inevitable, he said.
“In a democracy you always have people against you, and rallies are an integral and normal part of having a democratic system,” he said. “Russia said, ‘You see, you have internal problems.’ That’s the difference. In Russia, it is an internal problem. To us, it is a democracy.”
The police presence during the rally was light, and officers were not wearing helmets or armor, or visibly armed. Many chatted amiably with demonstrators.
But there were brief shoving matches between demonstrators and the police at the entrance to one government building, and allegations of police misconduct on the roads leading to the capital from the south and west, with several demonstrators saying that officers tried blocking cars and seizing keys and driving licenses.
Shota Utiashvili, a senior official in the Interior Ministry, said that he had received no complaints of police misconduct.
“So far that information has not come to us, but if there are any complaints we will investigate them,” he said.