Ukraine's furiously contested presidential election ended in a dead heat Monday, forcing a runoff between a pro-Russian candidate and his reformist challenger. Thousands of demonstrators in western Ukraine alleged fraud, and international monitors said the country failed the test of democracy.

The runoff, set for Nov. 21, prolongs a campaign that has been overshadowed by worries over irregularities. The vote is seen as key to whether the former Soviet republic moves closer to the West or to Russia. The winner will succeed outgoing President Leonid Kuchma (search), who clamped down on opposition during his rule.

The United States had warned it may take punitive action if the voting was marred by irregularities. Ukraine, which has a brigade of troops in Iraq, has been one of the top recipients of U.S. aid.

With 94.4 percent of precincts counted, pro-Kremlin Prime Minister Viktor Yanukovych (search) had 40.12 percent and top opposition leader Viktor Yushchenko (search) had 39.15 percent, the Central Election Commission said, describing the tally as unofficial preliminary results. The commission said turnout was around 75 percent but did not say when a total vote count would be announced.

Because no candidate won more than 50 percent in Sunday's vote, the race will be decided in the Nov. 21 runoff between the two men. Twenty-four candidates were in the first round.

Ukraine, a country just smaller than Texas, sits flanked by an eastward-expanding NATO and European Union and the surging economic power of its neighbor to the north and east, Russia.

While a Yanukovych victory is expected to move Ukraine toward closer relations with Russia, Yushchenko would like nudge the former Soviet republic of 48 million people to the European Union and NATO. Both candidates have promised to push for more growth in the country where millions still live in poverty although boasting strong economic revival after years of post-Soviet economic chaos.

Yushchenko's supporters have alleged widespread official intimidation and interference. His opponents claimed he was aiming to spark civil unrest and seize power. Yushchenko's allies announced they will file more than 70 complaints to the election authorities.

Lawmaker Yury Klitchkovsky, an ally of Yushchenko, said the results were "a massive falsification."

In the western city of Lviv, at least 5,000 Yushchenko supporters alleged election fraud, chanting "Enough with thieves" and "Power to clean hands."

Mykola Tomenko, a Yushchenko ally, warned of possible "rallies, strikes and demonstrations to protect people's rights" if Yanukovych won a fraudulent vote.

Foreign monitors representing European organizations said the vote failed to meet democratic standards, citing state media bias in favor of Yanukovych and state interference, including obstruction of opposition activities.

"With a heavy heart, we have to conclude that this election did not meet a considerable number of OSCE, Council of Europe and other European standards for democratic elections," one of the lead observers, Bruce George, said in a statement. OSCE stands for the Organization of Security and Cooperation in Europe (search).

"Ukraine now has three weeks to show that it is willing to organize democratic elections in accordance with its commitments," said Doros Christodoulides, an observer with the Council of Europe.

The group's preliminary report said voter lists had errors and omissions, including some cases of dead people listed as registered voters.

Stepan Gavrish, Yanukovych's representative at the Central Election Commission, dismissed the report as "more emotional than real."

Yanukovych's detractors claim that Ukraine will continue to suffer from corruption and nepotism they say was rampant under Kuchma and allowed a relative few to become extremely wealthy. They also fear Yanukovych, like Kuchma, will try to clamp down on the opposition and independent media.