* Election ends Saakashvili's decade in power
* Governing coalition's candidate expected to win
* Prime Minister Ivanishvili plans to step aside
By Margarita Antidze and Timothy Heritage
Georgia voted for a new president on Sunday in an election that will bring the curtain down on Mikheil Saakashvili's decade-long rule but is unlikely to end political uncertainty in the former Soviet republic.
The front-runner to replace Saakashvili, a pro-Western leader who has served the maximum two terms, is Georgy Margvelashvili, a member of the Georgian Dream coalition which ousted the president's cabinet in an election a year ago.
Saakashvili's departure should end feuding that has hindered policy-making and the investment climate, and cement Georgian Dream's hold on power, but the future is clouded by Prime Minister Bidzina Ivanishvili's decision to step aside as well.
The imminent retreat of Ivanishvili, the nation's richest man and Georgian Dream's leader, increases uncertainty in a country that is strategically important for Russia and Europe, which gets Caspian oil and gas through pipelines via Georgia.
"I'll vote for Margvelashvili of course. He's a new type of politician, a new generation," Gogi Popkhadze, 35 and unemployed, said as he voted in bright sunshine in the centre of the capital Tbilisi.
Tsira Gabrichidze, a 68-year-old pensioner, said she remained loyal to Saakashvili and voted for David Bakradze, a former parliamentary speaker from the president's party.
"We need a balance and I think it will be good to have a president from a party that is different from the ruling coalition," she said in Tbilisi, where dilapidated homes stand beside modern offices, underlining Georgia's economic problems.
Ivanishvili, 57, entered politics in the South Caucasus country only two years ago after making a fortune in business, but says his job will be complete when Saakashvili departs.
After the election, constitutional changes take effect which will shift power from the presidency to the government and parliament. No major policy changes are expected but Ivanishvili has not said who will be prime minister.
"This is not only a presidential election, but it's also a major change in the political system in Georgia," said Helen Khoshtaria, an independent political analyst.
CONCERNS ABOUT INSTABILITY
The arrest of several former ministers, including ex-Prime Minister Vano Merabishvili and dozens of other former officials, has alarmed Europe. But Ivanishvili denied on Friday that he would seek to jail his rival, and said he would not dictate the government's actions after he leaves office in about one month.
Opinion polls put Margvelashvili, a former vice premier, ahead of Bakradze and Nino Burjanadze, a leader of the bloodless 2003 "rose revolution" that ousted Eduard Shevardnadze.
The campaign, in contrast to many previous elections in post-Soviet Georgia, has been peaceful and failed to stir emotions, although Burjanadze hinted she feared foul play.
"All preliminary results, real results, not manipulated, not falsified, prove there should be a run-off," she told reporters after casting her ballot in the capital.
Margvelashvili, 44, has said he is confident of winning more than half the votes, enough to avoid a run-off, and that he will drop out of the race if he does not win outright on Sunday.
He presented a vote for himself as a vote "for the future prosperity of this country, for the future of our nation and for a better tomorrow."
A little-known politician dependent on Ivanishvili, his main foreign policy goal is to pursue close ties with the West and with Russia - a balance the country has long failed to achieve.
Under Saakashvili, who became president after the "rose revolution", the country of 4.5 million fought a five-day war with Russia in 2008, from which Moscow emerged in control of two rebellious Georgian regions. relations with Russia remain tense.
He won plaudits for reducing corruption and bureaucracy, and for launching economic reforms, but was criticised for not overhauling the justice system and poverty remains a problem.
After years of robust growth, gross domestic product grew only 1.5 percent in the second quarter this year, down from 8.2 percent in the same period a year ago.
Georgia allied itself with Washington under Saakashvili and pushed to join NATO, still a distant prospect. Georgian Dream has taken a similar path but sought better ties with Russia.