The specter runs counter to hopes in Brussels that the EU can diversify its energy supplies away from Russia amid fears the Kremlin might be trying to gain political clout over the West.
Putin's visit to the EU's newest member state is all about energy, which can't help but worry other members of the European bloc.
The Russian president will try to confirm Sofia's participation in a major new gas pipeline project dubbed South Stream. The pipeline -- jointly proposed by Russia's Gazprom and Italy's Eni -- would carry Russian gas under the Black Sea to Europe via Bulgaria.
The project would represent a direct challenge to the majority EU opinion that the bloc already is far too dependent upon Russia as an energy supplier. The EU currently gets some 40 percent of its imported gas from Moscow, and some European countries also get one-third of their oil from Russia.
Many European leaders worry that gives Moscow increasing political and economic leverage at a time when East-West tensions are on the increase. Brussels has watched Moscow apply energy price hikes to governments in Ukraine and Georgia that try to move closer to the West, and those showdowns to the east have caused disruptions further downstream in Europe itself.
Brussels is now trying to diversify supplies away from Russia by supporting a southern pipeline to bring energy to Europe from the Caspian Basin. That pipeline, via Turkey, would bypass Russian territory to connect Europe to the energy-rich former republics of the Soviet Union.
But the EU-favored pipeline, dubbed Nabucco, has been delayed by political problems and economic uncertainty. And that has provided Moscow with an opening to press ahead with yet another pipeline to Europe.
European Commission spokesman Ferran Tarradellas Espuny told RFE/RL in Brussels that the EU is committed to finishing Nabucco, but he said that does not mean it opposes the Russian initiative.
"Certainly the [European] Commission considers Nabucco as a priority for the commission because it is going to bring gas from a different region through a different transport route and it is going to increase the competition in the European market and the security of the market and certainly this is the priority of the Commission," Tarradellas Espuny said. "But the commission is not against other people wanting to make pipelines. If they want to do them, it is their choice to do it and for us, in principle, it will only mean more gas coming from the same supplier -- it is more security of supply."
He added that "the demand for gas in the European Union is going to be very huge, so any addditional supply will be welcome."
The South Stream pipeline would run under the Black Sea from Russia to Bulgaria's port of Burgas before continuing in several directions: toward Austria, toward Greece, and toward Italy.
Bulgaria's Bind
Just where Sofia should stand in the EU-Russia energy contest is hotly debated in Bulgaria. Sofia is firmly inside the EU but also is historically one of Russia's closest European partners.
The historic ties will be much on display during Putin's visit as Russian and Bulgarian officials mark a key Bulgarian anniversary. It 130 years since the Russo-Turkish War of 1877-78, during which Russian forces liberated Bulgaria from five centuries of Ottoman domination.
Bulgaria's Socialist-led government has argued for the new Russian pipeline, saying it will be a valuable source of transit fees for Sofia. However, the government is still far from signing a deal with Moscow, saying it will insist on holding a majority stake in any pipelines on its territory.
While the government is concentrating on such economic questions, the opposition is focusing on fears that Sofia is moving politically too close to Moscow. The right-wing opposition party Democrats for a Strong Bulgaria has called for a protest on January 17 in Sofia's central park, where the first anticommunist demonstrations were held in 1988.
During Putin's visit, Russia and Bulgaria are expected to sign a 4 billion-euro ($5.9 billion) energy deal, unrelated to gas or oil, that will cover the construction of a new nuclear plant at Belene on the Danube.
