By Richard Balmforth
KIEV (Reuters) - Ukrainian President Viktor Yanukovich's pro-business ruling party seems likely to win parliamentary elections on Sunday, but will face a re-energized opposition which has vowed to fight growing authoritarianism and corruption.
The former Soviet republic of 46 million is more isolated internationally than it has been for years. The imprisonment of former Prime Minister Yulia Tymoshenko, Yanukovich's main rival, has put it at odds with the United States and European Union, while Russia turns a deaf ear to Kiev's calls for cheaper gas.
At home, the government's popularity has been hit by tax and pensions policies and a failure to stamp out corruption, prompting it to shy away from painful reforms that could secure much-needed IMF lending to shore up an export-driven economy.
Despite this and growing apathy among an electorate tired of political bickering, opinion polls have shown Yanukovich's Party of the Regions leading the joint opposition, which includes Tymoshenko's Batkivshchyna (Fatherland) party, and a liberal party headed by boxing champion Vitaly Klitschko.
Commentators expect Regions, bankrolled by industrialists and drawing on state resources, to keep a majority in the 450-seat assembly with support possibly from communists and some independents.
"We have rebuilt the country, we have achieved stability," Mykola Azarov, prime minister and formal leader of the Regions, told a close-of-campaigning rally on Friday.
Even if it wins, Regions faces a tougher time in parliament.
Klitschko, WBC world heavyweight champion, who heads the UDAR (Punch) party, says he will team up with the opposition led by former economy minister Arseny Yatsenyuk to fight corruption they say deters entrepreneurial spirit and foreign investment.
From her jail in Kharkiv in Ukraine's northeast, Tymoshenko issued a statement that Yanukovich, who comes up for re-election in 2015, would set up a "dictatorship and never again give up power by peaceful means".
Tymoshenko was jailed for seven years last year for abuse of office relating to a 2009 gas deal with Russia she made when she was prime minister. The Yanukovich government says the agreement saddled Ukraine with an enormous price for gas supplies.
RUSSIAN LANGUAGE PROMISE
The government raised public sector wages and pensions ahead of the vote, recovering some of its lost support at the cost of widening the budget deficit which tripled to $2 billion for the period of January to August year-on-year. Ukraine's economy is vulnerable to falling demand for steel and other exports.
The Regions has also promised to make Russian an official state language alongside Ukrainian - a move aimed at winning back disenchanted supporters in Russian-speaking areas of the east and south but which alienates many voters elsewhere.
Polling stations will open at 8 a.m. and close at 8 p.m (1800 GMT) with exit polls following swiftly afterwards.
Of 450 seats in the single-chamber parliament, 225 will be filled by voters casting ballots for parties to send candidates from a list.
The other half will be decided by voting for individual candidates on a first-past-the-post basis - a feature re-introduced by the Regions which is assumed to favor the party.
Though results will begin to trickle in almost immediately, an accurate overall picture will emerge only much later on Monday since counts in individual constituencies takes longer.
International observers from the OSCE European security and human rights body are due to give their judgment on Monday on how fair and free they perceived the poll to have been.
A positive assessment could improve Yanukovich's image before Ukraine takes over the organization's chair in January.
(Writing by Richard Balmforth; Editing by Jon Hemming and Jason Webb)