Ukraine's interim government promised a clean presidential election on Sunday that would anchor the former Soviet state in the Western camp and show the world it would not be intimidated by after weeks of violence.
Russian President Vladimir Putin said on Saturday he would respect the choice of the Ukrainian people and would work with the new authorities. Moscow wanted stability, he said.
In the eastern region where at least 20 people have been killed in the past few days, pro-Moscow separatists said on Saturday they did not recognize a vote organized by authorities in Kiev they say took power in a Western-backed coup and officials said many electoral districts would be out of action.
Electoral officials in the east were setting up polling stations but fearful of violence which may keep people at home.
That could dent what the government hopes will be a massive nationwide turnout to give a mandate for closer ties with the EU and force Moscow to deal with a Kiev leadership that took power three months ago when the elected president fled to .
Having annexed Crimea in March on the grounds of protecting ethnic Russians from Ukrainian "fascists", Putin said Russia wanted a new constitution - something Kiev sees as a means to break the country up by handing more autonomy than it is willing to concede to Russian-speaking regions in the east.
"By all means, we will respect the choice of the Ukrainian people and will be working with authorities formed on the basis of this election," Putin told foreign journalists during an international economic forum in St. Petersburg.
Western powers have threatened further sanctions if Moscow impedes the ballot and Putin acknowledged on Friday that U.S. and EU measures were hurting the Russian economy.
Polls show almost certain victory, possibly outright in the first round, for confectionery magnate Petro Poroshenko, a former government minister who backed the pro-Western Maidan protests that toppled President Viktor Yanukovich in February.
Former premier Yulia Tymoshenko, also a supporter of closer ties to the EU, is a distant second but is the favorite to contest a runoff if Poroshenko - who is 48 and widely known as the "chocolate king" - fails to pass 50 percent on Sunday.
EU DEAL PRIORITY
Western-backed Prime Minister Arseny Yatseniuk told Ukrainians they had a responsibility to vote and assured those in the east whose ability to vote was being hampered by "the war against " that they would soon be free of "bandits".
"Tomorrow we will demonstrate to the whole world, but above all to ourselves, that we cannot be intimidated," Yatseniuk said in a televised statement.
He avoided mention of any candidate - campaigning is banned until voting ends. But he said he was sure the winner would make a priority of signing up to a closer alliance with the European Union - a move which Yanukovich rejected in November, triggering months of protests in Kiev that ended when he fled the country.
Saying the new president's first visit would be to Brussels to sign a free trade deal with the EU, Yatseniuk said:
"The newly elected president will receive from the Ukrainian people a mandate for a determined and unstoppable movement away from the grey zone of lawlessness and dark forces that dream of suffocating us and into an area of free people, rallied around common values - to a place where it is easier to breathe."
Many Ukrainians, especially in the east where businesses trade with Russia and fear competition from the West, are wary of opening up the economy to the EU, though many in the nation of 45 million would like to be able to travel freely in Europe.
Putin, whom critics say is bent on restoring Moscow's Soviet empire, is keen to bring the second most populous republic of the former USSR into a trading bloc with Russia. The tug-of-war over has created the gravest crisis in East-West relations since the end of the Cold War more than 20 years ago.
Keeping up a war of words with Moscow against a background of Russian and NATO buildups around Ukraine's borders, the Ukrainian foreign ministry issued a statement on Saturday saying border guards had seized armed men in several vehicles trying to cross the frontier from Russia illegally overnight.
"The penetration onto Ukrainian territory of armed terrorist groups, organized by the Russian authorities, is nothing other than the latest act of aggression against our state and a cynical breach by Russia of the norms and principles of international law," the ministry said, calling on international powers to take urgent measures to protect the election process.
Yatseniuk offered assurances the government had taken care to prevent electoral abuses seen in 23 years of post-Soviet independence that have seen Ukraine earn the dubious distinction of being named the most corrupt country in Europe.
Over 1,000 observers from Europe's OSCE security watchdog will monitor the vote, which will run for 12 hours until 8 p.m. (1300 ET). Exit polls will give a rapid indication of the result but a definitive outcome will only be known on Monday.
Holding the election would itself be a national victory, the prime minister said. "Remember, tomorrow, with our ballot papers, we will be defending Ukraine, investing in its prosperity and in the future of our children and grandchildren.
"We will vote, and that means we will triumph," he said.
FEAR IN THE EAST
In the city of Donetsk, capital of the Russian-speaking industrial Donbass area, people are deeply divided, with many keen to vote and remain in Ukraine and others hoping that a makeshift referendum held by rebels two weeks ago will let them follow Crimea into union with the much wealthier Russia.
Calling the Kiev authorities "worse than the Nazis", a pensioner who gave his name as Dmitry said outside the rebel-occupied regional administration building in Donetsk, "We are living under occupation ... Of course I'm not going to vote."
But another nearby, a 74-year-old called Anatoly, was equally contemptuous of those who have turned the building into the headquarters of their self-proclaimed People's Republic of Donetsk. Glaring at the barricades and rebel flags, he said:
"This is all nonsense, absolute nonsense. I'm against all of this - I can't believe they are acting against the Ukrainian state. They are Ukrainian fascists."
Saying he would not be able to cast a ballot, he added: "I have a right to vote. But they have taken away my right."
The Interior Ministry in Kiev said only four of 12 voting districts in the Luhansk region would operate on Sunday and 13 out of 22 in Donetsk. In principle, people can travel to cast votes elsewhere - as can people from Russian-annexed Crimea. It is unclear how many will risk trouble on the roads to do so.
Even in eastern towns where voting will go ahead, officials said some polling stations would not operate.
In the port of Mariupol, in the south of Donetsk region, a local electoral official, Viktor Kovba, said at least 10 of the city's 100 stations would not open and more might be affected.
"The head of one polling station of mine was beaten," he said. "There's a risk the election will be disrupted. It wouldn't take much. If they target three stations, the whole city will know immediately and people won't go to vote."
Nonetheless, he said he thought a 50 percent turnout in Mariupol was possible, about two thirds of previous levels.
At a polling station on the outskirts of the city, the person in charge, Ina Odnorug, said preparations had been held back to the last minute to avoid sharing the fate of three locations which had been attacked and their documents torn up.
"We are getting the ballot papers only tonight so they are not taken away," she said. A colleague who gave her name only as Viktoria added: "People are afraid."