Who can forget the pockmarked face of Ukrainian President Viktor Yushchenko after his soup apparently was poisoned by dioxin during the recent presidential campaign?

Tens of thousands of Ukrainians demonstrated peacefully against the rigging of the election in favor of Yushchenko’s opponent, who was openly backed by Ukraine’s big neighbor, Russia. Miraculously, grass-roots pressure worked — with European and U.S. support. A rematch on Dec. 26 reversed the election results.

Recently, at the World Economic Forum in Davos, Switzerland, I asked now-President Yushchenko the $64,000 question: “Do you know who tried to kill you?”

“I personally know who did it,” he said. “The circumstances of the dinner are very specific.”

“Will the trail lead to Moscow?” I asked.

“Can I refrain from answering?” he replied.

This cautious response holds the key to the spread of democracy on the fringes of Europe — and in Russia — in the coming years.

Ukraine’s Orange Revolution has become the inspiration to beleaguered liberals living in today’s Russia, and in other former Soviet republics with repressive regimes. Young people from Belarus, the last Stalinist state in Europe, flocked to the Kiev demonstrations. Moldovans, beset by criminal mafias, also are watching.

At Davos, Yushchenko talked of a new day for Ukraine, with a free press, rule of law, and a crackdown on a sickening level of corruption.

But will Russia try to undercut him? Ukraine depends on Russia for its energy supplies. The Kremlin also can stir up trouble within the large population of ethnic Russians in Ukraine.

Why does Ukraine make Russian President Vladimir Putin so nervous? One key reason: Ukraine now has become a model for the Russian political opposition.

Russia has moved back to authoritarianism under Putin. But Russians saw the Orange Revolution unfold on television, despite the Kremlin’s tight control of the electronic media. Some say that the Kiev demonstrations inspired ongoing street protests in Russia against cuts in social spending.

Another reason: Yushchenko wants to change the way Ukraine’s government operates. He declared at Davos that foreign investors would no longer have to pay bribes to do business. He promised to reform a system in which a phone call from a government official to a judge could ensure a verdict.

In a country in which journalists have been murdered — including the notorious beheading of investigative reporter Heorhiy Gongadze — Yushchenko says things such as: “You can’t talk of democracy in any country without a free press.” Many suspect that the active probe into the Gongadze case will lead to high officials in the government of the previous president, Leonid Kuchma, possibly to Kuchma himself.

Such brave pledges can’t sit well with Putin, whose Russia is also a haven for corruption, and many journalists have fallen victim to unsolved murders. Condoleezza Rice was correct, on her first overseas trip as secretary of state, to underline U.S. support for democratic processes in Russia’s neighborhood.

Yushchenko knows he has a big problem with Russia. His first foreign visit was to Moscow, where, he said, “I told Mr. Putin that the main thing we have to do is turn this page over.” The Ukrainian leader wants to “revitalize good relations with Russia, even for those frustrated by Russia’s behavior.”

No one knows whether Yushchenko will dare to follow the dioxin trail if it leads into the Kremlin. At a dinner at Davos, he offered a toast, joking that it was necessary to click glasses so drops of his wine would splash into the glasses of his fellow diners.

So long as such jokes are germane, Yushchenko will need strong U.S. and European support.