KIEV, October 23 (RIA Novosti) - Ukraine's opposition Party of Regions will gather on Friday to officially nominate as presidential candidate its leader Victor Yanukovych, seen as a frontrunner in the forthcoming elections.

Ukrainian pollsters say none of the candidates is likely to gather 50% plus one vote, required to avoid a runoff.

Recent surveys give Yanukovych, a former prime minister widely seen as pro-Russian, a 10-12% lead over Prime Minister Yulia Tymoshenko. She has about 15% and former parliamentary speaker Arseniy Yatsenyuk is placed third with some 9%. However, up to 25% of voters are uncertain about their vote in the second round, making the final result less predictable.

Tymoshenko is to formally announce her participation in the elections on Saturday, during a rally on Kiev's Independence Square (Maidan Nezalezhnosti), the main venue of street protests against alleged ballot rigging, which swept President Viktor Yushchenko to power five years ago.

Yushchenko, who defeated Yanukovych in an election re-run, now trails with under 10%.

The country's Central Election Commission will stop registering presidential candidates on November 9.