Bulgarians voted Sunday on whether to revive plans ditched by the government to construct a second nuclear power plant, in the EU member's first referendum since communism.
The vote was seen as a popularity contest for political parties ahead of elections in July, even though very low turnout was expected to render the result invalid.
Although the referendum does not mention it explicitly, at stake is the on-again, off-again 2,000-megawatt Belene power plant on the Danube river in northern Bulgaria that was first mooted in 1987.
Severe financial constraints and a lack of foreign investors after the 2009 withdrawal of German energy giant RWE prompted Prime Minister Boyko Borisov's right-wing government to abandon the project last March.
The opposition Socialists initiated the referendum after Atomstroyexport, the state-owned Russian firm set to build Belene, filed a compensation claim for one billion euros ($1.3 billion).
The referendum must have a turnout equal to that of the last general elections, or 4.35 million voters out of the 6.9 million eligible to do so, to be valid.
Surveys however suggest that this will be a tall order, indicating that a mere 1.6 to 2.1 million would vote, with 60-62 percent in the "yes" camp and 38-40 percent against.
By 1:00 pm (1100 GMT), seven hours into voting, turnout was just 9.34 percent compared with 29.31 percent at the same time in the 2009 general election.
Apathy abounds, and most voters are uncertain about the project's economic feasibility amid wildly different estimates for the cost of between 4.0 and 11.0 billion euros ($5.4-14.8 billion).
Both the former communist Socialist party and Borisov's GERB party however see the referendum as an important popularity test before the July general elections.
A recent Alpha Research poll showed waning support for GERB at about 21 percent, still ahead of the Socialists on 18.5 percent -- although their popularity has been rising.
Both sides are likely to claim victory in the referendum, even if the outcome is invalid, analysts said.
"Those who support Belene will declare success as the 'yes' votes will prevail," MBMD analyst Mira Radeva said.
"Those who are against will highlight the fact that the majority of voters failed to back the project by abstaining," she added.
The government has already announced plans to extend the operational life of the two 1,000-megawatt reactors at Kozloduy, Bulgaria's only nuclear plant, beyond their 2017 and 2021 deadlines.
It is also considering adding a new reactor to the Soviet-built plant, which was partially mothballed under pressure from Brussels on the eve of Bulgaria's accession to the European Union in 2007.
Kozloduy still generates 34 percent of all electricity produced in the country, allowing Bulgaria to keep its position as a top electricity exporter in the Balkans.
The Belene project was a priority for Atomstroyexport as its first in an EU member state.
Critics however have warned that it would strengthen Moscow's energy grasp on the small former Soviet bloc state, which gets almost all of its oil and gas from Russia.
Polling was due to end at 7:00 pm (1700 GMT) with exit polls expected soon afterwards.
If participation exceeds 20 percent, and over half of them vote "yes," parliament will have to review the issue within three months. But it is not obliged to revive the deal.