KIEV, Ukraine – Viktor Yushchenko, whose victory in Ukraine’s presidential election was all but assured yesterday despite his opponent’s threat to appeal the outcome, is expected to move quickly to bolster ties with the West while trying to ease tensions with Russia.

Yet there are questions about how fast he can open up to the European Union, NATO, and other Western structures, pursue plans for an ambitious economic overhaul, and tackle widespread corruption.

Six months of electoral wrangling have left the country bitterly divided between Ukraine’s west and a Russian speaking east, a region that backed Prime Minister Yanukovich in Sunday’s vote and remains angry that his victory in a November 21 ballot was overturned. Mr. Yushchenko also heads a political coalition whose factions are not united in their goals.

With nearly all ballots counted from an election that saw a 77% turnout, Mr. Yushchenko had just over 52% of the votes and Mr. anukovich had 44.2%.

Speaking at Kiev’s Independence Square, where mammoth crowds gathered for weeks to protest fraud in last month’s election, a jubilant Mr. Yushchenko told supporters: “Thousands of people that were and are at the square were not only waiting for this victory but they were creating it.”

Mr. Yanukovich refused to concede defeat, telling reporters he would go to the Supreme Court to challenge the results once the election commission released its final tally.

Later, however, he said he had lost respect for the court over its ruling that annulled the results of the earlier election, which Mr. Yushchenko’s camp, international observers, and even members of the Central Electoral Commission assailed as fraudulent.

“It breached the constitution and the law,” Mr. Yanukovich said of the court. “Today, I can’t have faith in such a chamber.”

An international observer delegation said that with Sunday’s revote Ukraine had made good progress toward meeting international standards for elections.

“It is our judgment that the people of this great country have made a great step forward to free and fair elections by electing their future president,” said Bruce George, head of the delegation from the Organization for Security and Cooperation in Europe, the Parliamentary Assembly of the Council of Europe, and other election watchdogs.

Thousands of people celebrated on Independence Square last night, but their numbers were far smaller than the hundreds of thousands who jammed the plaza at the height of the protests last month. “Today is a golden day,” said 62-year-old Mykola Rak, who was sporting an armband of orange, Mr. Yushchenko’s campaign color.

European leaders congratulated Mr. Yushchenko on his victory, and Secretary of State Powell called it a “historic moment for democracy in Ukraine.”

Mr. Powell also called on Russia to work with the Bush administration in helping this former Soviet republic. “Let’s all join together now and see what we can do,” he said.

But there was no immediate comment on the election from the government of President Putin, which backed Mr. Yanukovich. Last month, by contrast, Mr. Putin repeatedly congratulated Mr. Yanukovich on his purported victory, even before the announcement of the final results that were later annulled.

Despite his leanings toward the West, Mr. Yushchenko must pay heed to the Kremlin and told journalists last week that “I have no intention of creating new problems” with Russia. He said his first foreign trip as president would be to Moscow.

Russia is Ukraine’s biggest trade partner and a major investor here, and it is extremely nervous about eastward expanding European institutions such as the European Union and NATO. Eastern Ukraine, where just less than half the country’s 48 million people live, also is intent on keeping close ties with the former imperial and Soviet ruler.

Mr. Yushchenko faces a rocky road as he prepares to become president, both medically and politically.

He was poisoned with a nearly lethal amount of dioxin, which he blamed on the government, and will need monthly blood tests to track how quickly the poison is leaving his body. Doctors have said they expect a gradual recovery, although they fear an increased long-term risk of a heart attack, cancer, or other chronic diseases.

The political team that Mr. Yushchenko is relying on to fulfill the dreams of millions of Ukrainians – who have turned his very name into a mantra of hope – is a cobbled-together coalition with vastly different ideas about how much power the presidency should have.

The coalition has cut its teeth in the rough-and-tumble Ukrainian Parliament, where filibustering and dramatic walkouts regularly trump compromise.

One of Mr. Yushchenko’s most stalwart allies, Yulia Tymoshenko, has said she wants the post of prime minister – but many Ukrainians, especially in pro-Yanukovich strongholds, scorn the radical lawmaker who has pushed a radical political agenda.

The long campaign also has deepened the rift between Ukraine’s Russian-speaking, heavily industrialized east and cosmopolitan Kiev and the west, where Ukrainian nationalism runs deep.