THROUGHOUT THE 1990s, it's been widely recognized that Ukraine's success is key to a stable, peaceful post-Soviet world. And throughout the decade, such success has proved elusive, as Ukraine's economy has declined year by year. Now Ukraine is heading toward a fall presidential election that will go a long way toward determining the country's future course -- even, possibly, whether it survives as an independent nation. The United States has a strong interest in Ukraine's sovereignty and may even have a favorite in the election. But U.S. officials should make clear that they have an even stronger interest in the fairness and honesty of the election itself.

The nations that have done best in overcoming their Communist heritage are those that opted for quick and complete economic reform. Those that managed only partial reforms now find themselves in a dangerous way station. The old central command economies are gone, but a rule of law has not been established to make a real market economy work. This half-reform has given birth to powerful, corrupt elites that in turn have an interest in blocking completion of the reform process.

Ukraine and Russia both find themselves in this hard-to-escape netherworld. Ukraine is caught in the middle in other ways, too: geographically, between Russia and Central Europe; demographically, with large populations of ethnic Russians and ethnic Ukrainians; politically, with a Communist-leaning parliament that can stymie reforms proposed by President Leonid Kuchma.

Several presidential candidates have emerged from that left wing. They resent NATO, despite the World Bank and International Monetary Fund, and might even favor some kind of reunion with Russia and Belarus. Mr. Kuchma, running for reelection, presents himself as the candidate of reform and integration with the West, and he has skillfully managed both friendship with Russia and closer ties with the West. He has been a faithful partner in arms control.

There are worrying early signs, though, that Mr. Kuchma's team may overreach in its use of his incumbency, manipulating media, election machinery and other institutions to promote his reelection. Such behavior would only hurt Ukraine and its ties with the West, no matter who won the election. U.S. officials should make clear that no individual candidate matters more to them than seeing Ukraine stay on its democratic path. Unlike Russia and many other post-Soviet republics, Ukraine already has managed one peaceful transition; Mr. Kuchma is the second democratically elected president of the independence era. His backers should not sully that legacy.