Left-wing former rebels say that they have the upper hand in El Salvador's national elections.
The FMLN's Zamora is the new San Salvador mayor
All 84 seats in El Salvador's congress and 262 mayoral seats nationwide are being contested in the fifth election since a ceasefire ended a 12-year civil war in 1992.
The Farabundo Marti National Liberation Front (FMLN) said it had won 100 mayorships, and was gaining ground on the right-wing Nationalist Republican Alliance (Arena) in the congressional races.
Arena has conceded the city hall in the capital San Salvador, but said it had done better in the rest of the country.
Turnout was low, with only about 40% of the electorate casting their ballots.
The FMLN's candidate in San Salvador, Carlos Rivas Zamora, said late on Sunday that "our lead is clear enough to claim that we have won", although no official results have yet been released.
Arena party leader Archie Baldocchie said that, whatever its success in the capital, the FMLN had misread the rest of the country.
Unofficial projections estimate that Arena will maintain its 29 seats in Congress, while the FMLN could increase from 25 to 31.
Either party would need to enter into a coalition with smaller parties to gain a majority.
Voting was reportedly largely peaceful, but there were some irregularities.
Some polling stations opened late, and while some voters names had been left off the electoral register, deceased voters were still on the list.
The election is the fifth since 1992
"What a disgrace," said Salvadorian Maria Elba Vaquerano.
"I asked and they told me I was supposed to vote here, and now that I try they tell me my name is not there and that I can't vote."
In the run-up to the election several political activists were shot dead.
The sale of alcohol was banned for three days starting from Saturday morning.
Anyone caught drinking alcohol or selling it faces a fine of $114.