"One formulation reads that nobody can be deprived of their citizenship acquired by birth against their will," Arvydas Nekrošius, chairman of the working group, told reporters on Friday.
"The other proposal is to amend line 2 of Article 12 (of the Constitution) to read as follows: with the exception of cases provided for by constitutional law, no one may be a citizen of both Lithuania and another state at the same time," he said.
The working group expects to decide on the wording of the question next week and then start organizational work.
Currently, people who left Lithuania after it regained independence in 1990 cannot hold dual citizenship, apart from a few exceptions.
Article 12 now reads, "With the exception of individual cases provided for by law, no one may be a citizen of both the Republic of Lithuania and another state at the same time". That provision can only be amended by referendum.
The Constitutional Court has ruled that such cases can only be rare and, therefore, any law allowing dual citizenship for those who left after 1990 would run counter to the Constitution.
Lithuania's officials say that a dual citizen referendum could be held in tandem with next year's presidential election, but the Lithuanian World Community proposes to consider a later date, the 2020 general election, as an option.
Expatriates fear that a referendum on dual citizenship would fail as more than 50 percent of citizens would have to participate in the plebiscite and more than half of them would have to vote in favor for it to be legally valid.