Ukrainians went to the polls on Sunday in a tense presidential runoff pitting opposition leader Viktor Yanukovich against incumbent Prime Minister Yulia Tymoshenko.

Roughly 36 million registered voters are expected to cast their ballot at 34,000 polling stations, which opened at 8:00 a.m. local time (0600 GMT) and closes at 8:00 p.m. local time (1800 GMT). More than 4,000 international observers were monitoring the election, the local Inter TV reported.

Tymoshenko, accompanied by her husband Oleksander and daughter Yevhenia, cast her ballot at a polling station in Dnipropetrovsk.

"I have voted for a new Ukraine, a beautiful, European Ukraine in which people will live happily. I will be serving to Ukraine with all my heart," she said after voting, adding that she will be staying with her family on Sunday.

Yanukovich said he voted for good changes in the country. "I am sure that the Ukrainian people deserve better lives, which is why I have voted for good changes, for stability and a strong Ukraine," he told journalists after voting at a children's art academy in Kiev.

"We have already had enough of elections. I think today we are making the first, convincing step to overcome the crisis," he said.

Yanukovich, considered a pro-Russian politician, beat Tymoshenko 35.32 percent to 25.05 percent in the first round of votes on Jan. 17, but neither reached a 50-percent threshold to announce immediate victory. Both have been in fierce rivalry to become the country's fourth president since the former Soviet Union republic won independence in 1991.

Before the showdown, tensions have been mounting as there is increasing evidence that loser of the election would not concede defeat and might take supporters to street protests.

Born into a working class family in eastern Ukraine in July 1950, Yanukovich draws the bulk of his support from the Russian-speaking areas of the industrial east and the south. He has promised Ukrainians economic revival, new jobs, pay rises, judicial reforms and tax-free policies for small enterprises for five years.

Yanukovich, who heads the Regions Party, seeks mutually beneficial and friendly foreign policies, in contrast to outgoing President Viktor Yushchenko's active pursuit of NATO membership and anti-Russian policies.

Tymoshenko, born in November 1960, allied herself with Yushchenko in the 2004 "Orange Revolution" to overturn a controversial election initially won by Yanukovich. She became Ukraine's first female prime minister in 2005, but the shortlived political honeymoon with Yushchenko only lasted eight months. Tymoshenko was re-appointed prime minister in 2007.

The assertive woman is popular in the west of the country. She gave priority to a fair society and government efficiency, and pledged innovation-driven economic structure reform and improvement in people's welfare. She wants to move closer toward the European Union while keeping firm ties with Russia.

Both candidates face daunting tasks to shake the long-bickering politics into shape and pull the country out of a deep recession after making it to the presidency.

The exit poll figures, a rough indicator of the final election results, will be announced after polling stations are closed Sunday. Official electoral results will be published by Feb. 17 by the Central Election Commission.

According to the Ukrainian electoral law, the newly elected president should assume office no later than 30 days after the official results are out.