Kyrgyz President Almazbek Atambayev's party quit the ruling majority coalition on Monday over partners' refusal to back proposed constitutional reforms, deepening a rift that could destabilize the Central Asian nation.

The move by the Social Democratic party which backs Atambayev has will trigger creation of a new coalition and may lead to the resignation of the cabinet, parliament Deputy Azamat Arapbayev said.

Arapbayev, a member of the Social Democratic party, said the move was the result of other coalition members' refusal to support constitutional reforms proposed by Atambayev.

The proposed changes would strengthen the powers of the prime minister, a role which Atambayev could in theory take on after stepping down as president next year, although he said in August he had no such plan. The bill needs to be passed in the final, third reading to become law.

One member of the ruling coalition, the Ata Meken party, has opposed the reform and party leader Omurbek Tekebayev has become one of its most outspoken critics, arguing that the change would give the prime minister too much power.

Tekebayev was, along with Atambayev, among the leaders of the 2005 and 2010 protests which toppled two successive Kyrgyz presidents.

If the confrontation between the two extends beyond a war of words and parliamentary maneuvering, it could destabilize the volatile Muslim nation of 6 million which hosts a Russian military base.

The Social Democrat and Ata Meken coalition also included the Kyrgyzstan and Onuguu-Progress parties - which support the constitutional reform - and the bloc controlled 80 out of 120 seats in the parliament. Social Democrats on their own are the biggest faction, holding 37 seats.

Kyrgyzstan's parliament voted late September to call a referendum on constitutional change that would strengthen the powers of the prime minister, a move opponents say is aimed at getting President Almazbek Atambayev into the post when his term ends. The Central Asian nation's constitution bars Atambayev from running for a second term when his mandate ends in 2017.

The former Soviet republic's parliament passed a bill setting the referendum for Dec. 4. It will need to be passed in two more readings to become law. Atambayev's Social Democratic party leads the ruling coalition in parliament.

The proposed constitutional amendments include provisions granting more powers to the cabinet and to leaders of parliamentary factions.

Atambayev, 60, is being treated for suspected heart problems in Russia, but his office said this week he might return to Bishkek by next week. His illness followed a heated exchange with several former political allies who oppose the constitutional reforms.

Kyrgyzstan, an impoverished, mostly Muslim nation of 6 million, has been volatile in recent years.