BRAZZAVILLE, Republic of Congo (AP) — Republic of Congo citizens are heading to the polls to cast their vote on a referendum that could see the country's longtime president become eligible for a new term in office.

Under current laws, 71-year-old President Denis Sassou N'Guesso is barred from seeking re-election when his second term expires next year. The referendum asks voters to consider scrapping a two-term limit and 70-year-old age limit for candidates.

Electoral commission president Henri Bouka encouraged people to get to the polls Sunday, after what he said was a slow start. About 200 stood in line at a poll in Brazzaville.

Politicians campaigning against the referendum had called for a campaign of "civil disobedience," but by the end of the week called for calm. Four people were killed on Tuesday during violent demonstrations.