Western-leaning President Viktor Yushchenko dismissed parliament and called snap elections in the spring, accusing Prime Minister Viktor Yanukovych, his longtime foe, of usurping power. Following months of protests and court battles, the rival political groups agreed on the September 30 vote.
Latest polls put Yanukovych's Party of Regions, backed by the Russian-speaking east and south, in the lead with 33% of voter support. The Communists, their allies, are likely to make it into the 450-seat Supreme Rada enjoying 3.3% of support.
But Yushchenko and Yulia Tymoshenko, who led 2004 mass protests that swept the president to power and former prime minister, announced on Thursday they would forge an alliance after the polls.
"... There is only one option, which is to form a democratic coalition. Full stop. There will be no other coalition," the president said.
Tymoshenko's eponymous party and the pro-presidential bloc Our Ukraine-People's Self-Defense enjoy 22.7% and 13% of voter support respectively, according to opinion surveys.
But it is not clear whether their resolve will survive the election results and subsequent coalition talks. Yushchenko, who became president in early 2005, appointed Tymoshenko premier, but dismissed her eight months later amid scandals and internal frictions. Their alliance in parliament after the general elections in 2006 was also brief.
No other party among 20 listed on the ballot is likely to overcome the required 3% threshold. The Socialists, formerly within Yanukovych's parliamentary coalition, are unlikely to secure enough votes.
Some parties have meanwhile threatened mass rallies and new court battles to protest against possible vote rigging.
Yanukovych's supporters have set up a tent camp on Independence Square, the venue of "orange" rallies. On Friday, the final day for campaigning, the Party of Regions plans a meeting to be addressed by the premier and a concert on the square.
Yanukovych has been proactively campaigning in the past week traveling across the country by helicopter and addressing up to six meetings a day, Kommersant daily reported.
Opposition forces also plan final rallies for Friday. Pro-presidential supporters will gather near the Supreme Rada to listen to bloc leaders. And Tymoshenko bloc activists plan a prayer "for Ukraine" at the central square near St. Sophia Cathedral.
Yushchenko became president in early 2005 after a court overturned what it said was a rigged presidential election won by Yanukovych. Yushchenko has since sought membership for Ukraine in NATO and the European Union.
More Russia-friendly Yanukovych returned as premier after winning a majority in the 2006 parliamentary vote. He has been opposed to NATO membership, pledged to make Russian the second official language, but also vowed to pursue closer ties with Europe.
In their election programs, however, all parties focused on higher living standards for the ex-Soviet nation.