Liberians head to the polls Tuesday to vote on proposed constitutional changes that are backed by the ruling party and strongly opposed by the opposition.

The most controversial change would reduce the number of years a presidential candidate must have lived in Liberia from 10 to five.

That could affect which candidates are eligible for the coming election. Many politicians left the country during 14 years of civil unrest that ended in 2003.

Another change would delay the presidential election from October to November. Supporters say that move would take elections out of the rainy season, when travel is often difficult.

Members of the main opposition Congress for Democratic Change say the changes would benefit the ruling Unity Party and President Ellen Johnson Sirleaf. Many also say the referendum should not be held so close to elections.

Other proposed changes would raise the retirement age of Supreme Court justices from 70 to 75 and eliminate run-off votes in parliamentary elections.

Two-thirds of voters will have to approve the changes for them to be adopted.