Updated

Kazakhstan's long-serving president inched closer to securing another decade of unchallenged rule Friday after parliament opened the way for a referendum to scrap upcoming presidential elections.

A joint session of the lower and upper houses of parliament voted unanimously to change the constitution to allow the referendum.

President Nursultan Nazarbayev, who has ruled the country since independence from the Soviet Union, was to face re-election in 2012. But organizers of a petition drive to allow him at least 10 more years in power claim to have collected 5 million signatures, around half the electorate.

Supporters say he has ensured stability and economic prosperity, while detractors accuse his regime of corruption and undemocratic practices.

Nazarbayev has to approve the amendment. Presidential adviser Yermukhamet Yertysbayev said he was uncertain what Nazarbayev would do now.

Yertysbayev conceded that allowing the referendum would likely set Kazakhstan on a collision course with its international commitments to improve democratic standards.

"But parliament was unable to take any other decision since they represent the people, and 5 million people have supported this idea of referendum," he told The Associated Press.

The one-party parliament late last year put forth a motion to allow Nazarbayev to extend his term, which is currently limited to seven years by the constitution. But Nazarbayev swiftly rejected the proposal, raising expectations that the initiative might be dashed. But the success of the petition campaign now appears to have made the referendum inevitable.

Election officials validated almost all the 5 million signatures in the petition. That is vastly more than the 200,000 signatures required to call a referendum.

Opposition politicians have called for a closer scrutiny of the petition.

On the eve of the vote, the U.S. ambassador to the Organization for Security and Cooperation in Europe, a group that includes democracy promotion among its main goals, expressed grave concerns over the referendum plans.

"To cancel presidential elections once again in favor of a referendum would represent a step backwards from Kazakhstan's OSCE commitments to establishing democracy, holding periodic free and fair elections, and respecting the rule of law," Ambassador Ian Kelly told the OSCE permanent council in Vienna.

Kazakhstan has never held an election considered fair by the OSCE.

Despite the misgivings of his critics, Nazarbayev is genuinely held in high esteem by broad swaths of the population. It is uncertain, however, to what extent this accounted for the proliferation of posters showing his image around the country and relentless positive coverage on state media.

Kazakh authorities have in recent years been steadily installing what has been described by some as a cult of personality. Most notably, parliament voted last year to name Nazarbayev "leader of the nation," a title that effectively made Nazarbayev president for life.

As well as giving him the right to approve important national and foreign policies after he retires, the title grants him lifetime immunity from prosecution for acts committed during his rule.

Dissent is not tolerated and what few small-scale protests have taken place around the country have been swiftly quashed.

Earlier this week, a small group of young activists in Kazakhstan's commercial capital, Almaty, picketed the offices of the pro-government Nur Otan party, the only political grouping represented in parliament. They were dragged away by police within a few minutes.

In a swiftly summoned hearing Thursday, a court fined the participants more than $200 each for holding the unsanctioned meeting.

A similar protest in the city of Uralsk earlier this month led to the jailing of two activists.

For lack of access to the streets, some government critics have resorted to taking their discontent online.

A satirical cartoon posted Friday on YouTube to the accompaniment of a song mocking the referendum proposal ends with an on-screen message reading: "Make the right choice! Be a sheep and vote yes."

(This version CORRECTS Adds comment from presidential adviser, corrects that the current term is seven years, not five.)