* Pro-West rulers face powerful Communists
* Relations with Russia and Romania also at stake
By Richard Balmforth
CHISINAU, Nov 28 (Reuters) - Moldovans voted on Sunday in their third parliamentary election in just over 18 months, facing a choice of staying with the pro-Europe course of their liberal rulers or backing closer ties with Russia.
Wrestling with three-feet (94 cm)-long ballot papers reflecting a large field of 20 parties, voters cast their ballots in an election called to break political stalemate that has blocked reform in the small ex-Soviet republic.
The ruling Alliance for European Integration, a four-party coalition, has sought in the past 15 months to nudge Moldova, one of the poorest corners of Europe, closer to the European mainstream after eight years of communist rule.
But a powerful communist opposition has consistently stymied the Alliance's efforts to exert full control by blocking efforts to elect a full-time president who is voted in by parliament.
This in turn has kept Moldova, a European Union aspirant, from reforms the EU says are needed to join the bloc.
These include ending corruption, bringing institutions such as the judiciary and the police up to EU standards and encouraging the growth of an independent mass media.
Russia and EU member Romania have long vied for influence in Moldova, a tiny state of 4.1 million people.
Romania and other EU states largely back the Alliance's reform path, but Russia may be counting on the emergence of a left-centrist coalition, including the communists, to end a gradual slide in relations since the Alliance came to power.
On the eve of the vote, coalition leaders and communists traded insults, each side predicting victory for itself.
"We democrats took over a pig's trough from you communists but your chances of returning to power are zero. The people do not believe your lies," acting president Mihai Ghimpu told leading communist Iurii Munteanu in a television debate.
Most commentators said the election is too close to call.
The outcome could be a reaffirmation of the present impasse between the parties but a surge by the communists that might lead to a left-centrist government can not be ruled out.
MOSCOW'S HOPES
Support for the Alliance parties is strongest in the cities, but a deep nostalgia for Soviet times works to the advantage of the communists in rural areas.
Though Moldova relies exclusively on Russia for its gas, it fell foul of Moscow when Ghimpu, a strong critic of Russia, fixed a "Day of Soviet Occupation" in the political calendar.
Russia responded with restrictions on imports of Moldovan food, including wines which are Moldova's main export earner.
Communist leader Vladimir Voronin, a two-time president, steered a middle course between Russia and the West when he was in power and angered Moscow when he rejected Moscow's blueprint for a settlement in Moldova's Transdniestria region in 2003.
But commentators believe Moscow would prefer a coalition between the Communists and possibly the party of Marian Lupu, the one Alliance member who is closest to Russia.
A communist victory in an election in April 2009 sparked big street protests in Chisinau in which young people ransacked the president's office and parliament building. The communists lost the Alliance parties in a snap election in July.
"The only true chance is to pursue the reforms that have begun and which are supported by the EU, the United States, the IMF and the World Bank," Prime Minister Vlad Filat told Reuters. "We can not allow the return of Moldova to the past," he said.
Only four parties -- the Communists and three of the Alliance parties -- are expected to pass the 4 percent barrier for representation in parliament, but none seems likely to get the 50 percent required to form a government.
In July 2009 though the Communists confirmed their role as the biggest single party by winning 48 seats, the Alliance joined forces to take power with a combined 53 seats.
But this did not hand the Alliance a big enough majority in the 101-seat assembly for it to secure its choice as president.
"I voted for the Communists," said Ion Capmoale, a 67-year-old pensioner in Chisinau. "When they were in power, life was hard as well, but pensions were regularly raised."
Tatiana Untura, 32, said: "I voted for Vlad Filat. There is a lot he did not manage to do because you cannot in just one year correct everything that the Communists destroyed in eight years. But if today's rulers are given a chance they will sort things out." (Additional reporting by Alexander Tanas; Editing by Maria Golovnina)