Nabih Berri, the speaker of the Lebanese Parliament, postponed a regular session where lawmakers heard arguments over the voting age, Lebanon's Daily Star newspaper reports.
Beirut passed a series of electoral reforms in 2008, including campaign regulations and measures to conduct voting on a single day. Lawmakers passed a measure in March to lower the voting age to 18, but that was not in force for June parliamentary elections.
Christian lawmakers protested the voting-age issue during the weekend, trying to tie the measure to a procedure granting expatriates the right to vote.
Christians are among the minority for voting-aged adults compared with the Muslim population in Lebanon.
Ahmad Fatfat, a lawmaker with the Future Movement Party of Lebanese Prime Minister Saad Hariri, complained the two issues were mutually exclusive.
"Tying the two issues is illogical since lowering the voting age requires only a constitutional amendment after which it would be effective immediately, while allowing expatriates to vote requires the adoption of executive procedures which are still to be issued," he said.
Elections could take place as early as June.