Opposition leaders called for Kazakh President Nursultan Nazarbayev's election victory to be declared invalid, while Western-led observers said the vote that gave him 91 percent support was flawed.
Similar criticisms by international observer missions were key in establishing an air of legitimacy for mass protests that helped bring opposition leaders to power in the other former Soviet states of Georgia, Ukraine and Kyrgyzstan over the past two years.
But in oil-rich Kazakhstan, as in Azerbaijan's contested parliamentary elections last month, the opposition's options appeared to be limited by the comparatively authoritarian regimes they live under.
"We reserve the right to stage public protests, but we take into consideration the possible response from the authorities and we don't want innocent blood being spilled," Nazarbayev's main challenger, Zamarkhan Tuyakbai, said on Monday.
"We will take all necessary measures to appeal the results released by the Central Election Commission and declare the vote illegitimate,'' Tuyakbai said.
The Central Elections Commission said Nazarbayev won 91 percent of the votes in Sunday's elections, while Tuyakbai, his closest challenger, won 6.6 percent.
Nazarbayev, who has led the nation of 15 million since 1989 when it was still a Soviet republic, allowed some political reforms in the early 1990s. But analysts say he later backed away from that path.
Audrey Glover, head of the Organization for Security and Cooperation (OSCE) in Europe's long-term observer mission, rebuked him for failing to keep promises.
Glover said on Monday, "I much regret that the Kazakhstan authorities did not provide a level playing field for democratic elections. This happened despite assurances from the president that the elections would be free and fair."
The US also said that the elction in Kazakhstan did not meet international standards, though some improvements were shown over previous votes.
"They did some things well. There were other areas where they fell a little short," State Department deputy spokesman Adam Ereli said in Washington.
Ereli said the US generally shared the OSCE's view that the vote did not meet international standards for democratic elections. But, he said, "you don't go to perfect elections overnight.''
Much of the OSCE's criticism focused on the election campaign, saying the opposition was denied equal coverage in state media and its supporters faced intimidation, beatings and seizure of campaign materials. The OSCE also said evidence showed university students had been pressured by faculty to vote for Nazarbayev.