TBILISI, Georgia — Voters in Georgia on Sunday are choosing a new president for the former Soviet republic on the Black Sea, the last time the president will be elected by direct ballot.

Opinion polls before the election suggested that no one of the 25 candidates was likely to receive the absolute majority needed to win in the first round. If no one wins outright, a runoff between the top two candidates is to be held by Dec. 1.

After the new president’s six-year term is completed, future presidents are to be chosen by a delegate system, part of constitutional changes that make the prime minister the most powerful political figure in Georgia. The president functions as head of state and commander in chief, but the role is otherwise largely ceremonial.