57 lawmakers on Tuesday gave their initial backing to the proposal, 33 voted against and 14 abstained. The proposal will now go to parliamentary committees for consideration.
Under the proposal, the referendum threshold would be lowered for amending all articles of the 1st and 14th constitutional chapters. More than half of voters who turned out, but at least two fifths of all citizens with the right to vote, would have to say "yes" in a referendum to amend an article of Chapter 1 and Chapter 14 of the Constitution.
Currently, these chapters have a higher level of protection, and backing of at least half of all citizens is necessary to change them.
Around 2.5 million citizens are eligible to vote in Lithuania. Half of them would make 2.5 million, and two fifths would make 1 million voters.
The parliament's intention to lower the threshold has already come under fire from Lithuanian President Dalia Grybauskaitė. Mindaugas Lingė, the president's internal policy adviser, confirmed earlier in the day the president would veto the bill.
The idea to lower the threshold for amending the 1st and 14th constitutional chapters came into being after the Seimas backed the president veto in September the parliament's previously adopted amendments on relaxing requirements on the number of votes needed to amend Article 1 of Chapter 12 of the Lithuanian Constitution, defining citizenship.
The proposal to lower the threshold comes in preparation for a dual citizenship referendum planned to be held on May 12 and May 26, 2019, in tandem with the first and second rounds of voting in the next presidential election.
Currently, people who left Lithuania after it regained independence in 1990 cannot hold dual citizenship, apart from a few exceptions. That provision can only be amended by referendum.
Advocates of dual citizenship fear that such a referendum might fail due to low turnout unless the threshold is lowered.