ULAN BATOR, Mongolia — Standing down doesn’t come naturally to Elbegdorj Tsakhia, who was a 27-year-old newspaper editor in the winter of 1990 when in subzero temperatures he helped lead a series of mass demonstrations and hunger strikes here that ended seven decades of communist rule.

Now a seasoned politician with two stints as prime minister behind him, Mr. Elbegdorj is more sensitive to the limits of protest in this young democracy.

The 45-year-old leader of the nation’s leading opposition group, the Democratic Party, brought Mongolia’s government to a halt this summer by refusing to have his party members take their seats in Parliament following elections in June that he says were corrupted by widespread fraud.

The boycott came in the aftermath of one of the most violent episodes in recent Mongolian history. On July 1, protests over the parliamentary election results deteriorated into a rock-throwing and Molotov cocktail-tossing riot that left five people dead and two prominent buildings near the central square in charred ruins.

Over the next four days, the government, led by the formerly communist Mongolian People’s Revolutionary Party, imposed a nighttime curfew and shut down all television and radio stations but Russian and state-controlled channels. The unprecedented state of emergency raised fears that Mongolia, an island of democracy and a staunch American ally between two autocratic heavyweights, China and Russia, was slipping backward.

The Democratic Party responded in turn by demanding a vote recount in contested districts, an overhaul of election laws, and that those responsible for killing the five people (four of whom were shot and one beaten to death) be brought to justice.

A sparsely populated, landlocked nation with a vast countryside surrounding a traffic-clogged modern capital, Mongolia was heading toward political chaos. Mr. Elbegdorj defused the situation by negotiating a deal with his opponents.

“You cannot boycott everything endlessly,” he said in his most extensive interview to the Western press since the riots. Yesterday evening, lawmakers were sworn in, as Parliament session resumed and the political standoff came to a halt.

His decision to relent leaves Mongolia safely in the hands of Prime Minister Sanjaagiin Bayar and the MPRP, at least until the next parliamentary election in four years. The tensions between the two sides, however, have hardly simmered.

Mr. Elbegdorj points to a white board in the main conference room at his party’s headquarters, a squat, two-story, Soviet-constructed building that faces the east side of Sukhbaatar Square, where 18 years ago he stood with a microphone before more than 100,000 protesters and called on the entire Politburo to resign.

The board shows two columns of numbers: one that adds up to 64 and the other to 28. The first figure is the number of seats his party expected to win, and the second the disputed result, which was 11 seats short of a majority the Democrats needed to take control for the third time since 1990.

International election observers, including the Asia Foundation, declared the June 29 elections to be fair and generally free of tampering. Mr. Elbegdorj said his political rivals employed “sophisticated” tactics and insists the fraud started “from the production of the ballot paper and ended with the counting.”

He claims that some people voted as many as 18 times by using IDs of Mongolians living outside the country or in a distant province. One source of the problem, he says, is the domination of provincial election commissions, which oversee the balloting, by the MPRP, which has shared power nationally but has maintained tight control over local government.

In his view, the more serious abuses of power took place after the vote. The blackout of the privately run television stations allowed the MPRP to manipulate public opinion, he said. The only available broadcasts blamed Democrats for the mayhem and ignored the allegations of fraud.

He goes so far as to suggest that the ruling party literally fanned the flames of the riot. In the early hours of the curfew, after rioters set ablaze the five-story headquarters of the MPRP, a fire erupted at the nearby Mongolian National Modern Art Gallery, destroying valuable ivory and wood carvings. Mr. Elbegdorj says the second fire was not started by the protesters.

“The museum caught on fire in an organized way. It was made intentionally in order to blame people from the Democratic Party,” he said, saying the government was “trying to use people’s anger against those people who were in the demonstration, saying these were guys who were so violent they would even burn down a museum.”

To his critics, Mr. Elbegdorj is suffering from a case of sour grapes and is trying to make excuses for his party’s devastating loss.

The notion that the party had anything to do with the fire is absurd, the general secretary of the MPRP, Yondon Otgonbayar, said in a telephone interview. “You can’t think of a more stupid thing,” he said.

He also disputed the charge that the election was tainted by wide-scale fraud. “Every election always has a problem in every country. Whether it’s widespread, I don’t think so,” he said. “Each election has a winner and loser. A mere fact that someone is not happy about losing has nothing to do with democracy. Just because he lost, he can’t say the system is wrong.”

Mr. Elbegdorj says he extracted important victories from his peace pact. He ended his party’s boycott only after the ruling party agreed to form a new parliamentary subcommittee that will investigate the fraud allegations. The state prosecutor’s office has also launched a surprisingly aggressive investigation of the state police and has charged several officers with shooting demonstrators. Most important to him are polls showing that a majority of Mongolian voters say they believe the elections were unfair.

For Mr. Elbegdorj, who served briefly as prime minister in 1998 at the age of 35, after which he earned a master’s degree at the John F. Kennedy School of Government at Harvard University, the last couple of years have been filled with frustration and pain.

In 2006, after he was prime minister for two years, his coalition fell apart, a result, he says, of an anti-corruption campaign that ruffled too many feathers. Last year, he was critically injured in a car accident in which his driver was killed. Mr. Elbegdorj has since recovered.

The son of sheepherders from a western province, Mr. Elbegdorj came of age as a military journalist in Lviv, Ukraine, during the period of glasnost, when he turned his back on his formal communist instruction and embraced free-market and democratic principles.

He takes credit for privatizing the nation’s 35 million livestock and creating a 10% flat tax on corporate and personal income. But his other grand plans — particularly the promotion of English as a second language, an overhaul of the courts system, and the establishment of a fund to distribute to the people the wealth from the country’s enormous reserves of copper, gold, coal, and other minerals — were left frozen.

While displaying his pragmatic side this week, Mr. Elbegdorj is already plotting a comeback. He may step down as party leader and prepare for a run next year for president, the second-most-powerful position in government.

“This is a serious setback. We have to come up from this situation,” he said.