By Marja Novak
LJUBLJANA (Reuters) - Slovenians vote in a referendum on Sunday on whether the government should pursue construction of a 1-billion-euro ($1.20 billion) railway to its main Adriatic port - a test of the government's popularity ahead of elections next year.
Given the opposition's lead in opinion polls and criticism of the project as too expensive, analysts see possible changes in the center-left coalition government ahead of the elections in June or July 2018 if the railway gets a thumbs-down in the referendum.
"If (it) is rejected that would be a strong blow to the government, particularly the leading party SMC (Party of the Modern Centre)," Meta Roglic, political analyst at the daily Dnevnik, told Reuters.
Opinion polls have forecast varying outcomes of the referendum but suggest turnout might not be sufficient to block the railway project. A poll published by daily Delo said voters would narrowly reject the project, while another released by Dnevnik said voters would back it by a 53-29 percent margin.
Under Slovenian law, a minimum 20 percent of some 1.7 million eligible voters would be needed to sink the project, in addition to a majority of those voting.
Civil society group Taxpayers Don't Give Up and the leading opposition group, the center-right Slovenian Democratic Party (SDS), pushed for the referendum, saying the railway line as projected by the government is too costly.
The government says the 27-km (17-mile) rail link between Koper and the town of Divaca is necessary to speed up freight traffic to and from Slovenia's only port and improve the port's competitiveness.
The government has received 44.3 million euros in EU funding for preparation of the track while neighboring Hungary said it is willing to invest about 200 million euros as it relies on Koper for much of its seaborne freight.
The opposition SDS has led in opinion polls for most of the past year. But government parties hope to improve their ratings by advancing the railway project, raising family subsidies and the lowest tier of wages, and injecting more money into the state health sector in the coming months.
(Reporting by Marja Novak; editing by Mark Heinrich)