MOSCOW — If only Nikita S. Khrushchev hadn't been so generous rewarding Ukraine for its loyalty to Russia.

Forty years ago, the Soviet leader transferred Crimea from Russia to Ukraine. Now, Crimea's predominantly Russian and Russian-speaking residents want to go home again.

The results of today's second round of presidential voting will most likely make that possible, because a Russian secessionist is favored to win the presidency of the autonomous republic. The first round of voting, held two weeks ago, demonstrated the erosion of popular support for Ukrainian independence. A course that will put Ukraine on the path of civil war and open conflict with Russia may be set.

In December, 1991, nearly 55% of Crimean residents voted for Ukraine's independence. This outcome was warmly welcomed by politicians, because the Crimean peninsula's history and politics had easily made it the "most likely to secede" from Ukraine. During \o7 perestroika\f7 , when Ukraine was inching toward independence from Russia, the Crimean secessionist card was frequently played by various political factions to threaten the Ukrainian independence movement with the possibility of breakup and irredentist claims by Russia. But the '91 vote proved these threats empty, though not dead.

Two years of Ukrainian independence have taken a severe toll on Crimea and radicalized its politics. Nikolay Meshkov, the candidate who would reunite Crimea with Russia, received 38% of the vote in the first round. His chief opponent, who favors continuing union with Ukraine, got only 17%. Another 30% was divided among candidates who support some one form or another of distancing from Kiev.

If Meshkov is elected the first president of Crimea and follows through on his declaration to rejoin Russia, the threat of disintegration of Ukraine will be real and immediate. Even if a more moderate candidate prevails, the elections will have shown that the post-independence political consensus in Ukraine has fallen victim to hyperinflation and tardy reform, as well as to regionalism and nationalism.

U.S. policy-makers face some tough choices if Crimea moves to secede. Kiev has few options other than the use of force to preserve the union--a prospect that would almost certainly lead to escalation and some form of Russian intervention in the conflict. The recently concluded U.S.-Ukrainian-Russian agreement on nuclear weapons deployed in Ukraine would be the first, though least important, victim. More important victims include the pace of Russia's reforms, which is already slow, and chances for the survival of an independent Ukraine.