Bulgaria's parliament approved a law on Thursday to make voting compulsory in an attempt to boost election turnout and the legitimacy of political institutions.
The European Union (EU) member has had five governments since 2012. The last election in 2014 produced a 51 percent turnout, the lowest in 25 years, and a fragmented parliament.
A record eight parties won seats as increasingly disaffected voters turned their backs on the traditional political players.
Lawmakers from the ruling centre-right GERB party, and most of its allies, have now approved amendments to the Election Code that will make voting mandatory.
However, those who wish to abstain can still select a "not voting for anyone" option.
In January, parliament gave the green light to electronic voting, a move expected to help Bulgarians living abroad to take part in elections and encourage more young and educated people to vote.
Critics said that making voting compulsory was "unconstitutional" while the right-wing Reformist Bloc, GERB's smaller coalition partner, threatened to refer the parliament's decision to the Constitutional Court.
"We cannot oblige people to believe in us," said Radan Kanev, leader of the Democrats for Strong Bulgaria, one of the parties in the Reformist Bloc.
Under a draft proposal that is awaiting approval, unspecified incentives could be offered to those who cast a vote while those who do not would be removed from the electoral roll, forcing them to reapply before they can vote again.
A presidential election is scheduled for October and a parliamentary election in 2018.
In 2013, voter frustration with rampant corruption and organised crime led to months of street protests.
Concerns about corruption and the judiciary have prevented Bulgaria and its northern neighbour Romania from joining the EU's 26-nation Schengen zone of passport-free travel.