TBILISI, Georgia — Voters in Georgia are choosing a new parliament in a heated election Monday that will decide the future of President Mikhail Saakashvili's government.

His party, which has dominated parliament, is up against an opposition coalition led by Bidzina Ivanishvili, a billionaire businessman who has posed the most serious challenge to Saakashvili since he came to power almost nine years ago.

With fears of fraud running high, Saakashvili is under pressure to prove his commitment to democracy by holding a free and fair election. Both sides have promised to respect the results if the election receives the approval of international observers.

About 1 million of Georgia's 3.6 million eligible voters live in Tbilisi, the capital, where opposition support is strongest.

Under Saakashvili, the former Soviet republic has aligned itself with the United States, while striving to join the European Union and NATO one day.

Ivanishvili, who made his money in Russia, has said he would pursue these strategic goals while also seeking to restore the ties with Moscow that were severed when the two neighboring countries fought a brief war in 2008.

Saakashvili has accused him of serving Kremlin interests and intending to put Georgia back under Russian domination, which the opposition leader has denied.

After casting his vote on Monday, Saakashvili said the election was important not only for Georgia.

"A lot of things are being decided right now in our country, for the region, for the development, for the future not only of this nation, but for what happens to the European dream in this part of the world. What happens to the idea of democracy in this part of the world, what happens to the idea of reforms in this part of the world," he said.

The opposition has accused Saakashvili of authoritarian rule. His party, the United National Movement, holds 119 of the 150 seats in parliament.

Slightly more than half of parliament members, 77, are chosen based on how well the parties do in a vote based on party lists. The remaining 73 members are directly elected by majority vote in their constituencies.

The election sets in motion a change in the political system to give greater powers to the parliament and prime minister. After Saakashvili's second and last term ends next year, the party that holds the majority in parliament will have the right to name the prime minister, who will become more powerful than the president.