The opposition Jamaica Labour Party (JLP) appears to have won power in a cliffhanger election.
Election officials said the JLP won 31 of the 60 seats in parliament in a preliminary vote count, although the ruling People's National Party, facing the end of an 18-year reign, served notice it would likely challenge the result.
If the result stands, it would mean a quick end to the tenure of Portia Simpson Miller, Jamaica's first woman prime minister, who took over the leadership of the People's National Party 18 months ago.
Bruce Golding celebrates his apparent election victory at Jamaican Labour Party headquarters in Kingston.
JLP leader Bruce Golding, the veteran politician who would become prime minister if the result holds, cautiously sidestepped an outright claim of victory in a speech to supporters last night.
"However perplexing some may find the results, the fact is that the people have spoken, and we of the Jamaica Labour Party, we accept and respect the decision," he said.
"At the moment, the Jamaica Labour Party commands a majority of seats in parliament," he added.
But Ms Simpson Miller said she was not going to concede defeat before the results were final and had been examined closely. "As of now we are conceding no victory to the Jamaica Labour Party."
Citing voting irregularities, Ms Simpson Miller said PNP candidates could file legal challenges.
"In some constituencies people were barred from exercising their right to vote," she said, adding people were campaigning illegally and votes were bought. "We have this evidence."