Centrist Luis Guillermo Solis took a surprise lead in Costa Rica's presidential election Sunday, and will now face a ruling party candidate in a run-off vote in April.

Long considered the "Switzerland of Central America" for its peaceful and stable democracy, Costa Rica has seen a string of corruption scandals during the administration of outgoing president Laura Chinchilla, the country's first female president.

The scandals, combined with a sharp and growing income disparity between the haves and the have-nots, seriously hurt the official candidate.

With 76 percent of the ballots counted, Solis -- a historian by training and candidate for the Citizen Acton Party (PAC) -- won 30.8 percent of the vote, narrowly ahead of Johnny Araya from the ruling right-wing National Liberation Party (PLN), who had 29.6 percent.

In third place with 17 percent was the man everyone thought would be in the run-off, leftist candidate Jose Maria Villalta.

"We are going to win because we are a people that has decided to change!" a euphoric Solis told thousands of cheering supporters gathered at his campaign headquarters.

"A wave has risen like a great tsunami sweeping away traditional politics forever," he said.

Solis has never held political office and was largely unknown until months ago, though he has worked in several PLN administrations and once served as ambassador to Panama.

In early January, polls showed that Solis had only five-percent support among voters. His party, formed to fight corruption and support of better income distribution, is just 13 years old.

Solis's stunning rise was as surprising as the collapse of Villalta, who pre-vote polls showed as having a chance at bringing the political left to power in this conservative Catholic country for the first time.

Villalta had emerged as the leading anti-corruption, anti-establishment candidate until he faced a barrage of attacks from Araya, who portrayed him as a pro-gay marriage communist.

Villalta even faced death threats on the campaign trail, local media reported.

Chinchilla-era scandals weigh down Araya

While the 55 year-old Solis benefitted from Villalta's drop, Araya -- a 56 year-old long time mayor of the capital San Jose -- was dragged down by his association with Chinchilla and eight years of PLN government.

"There is no doubt that the results show that we have not yet given enough clear signs to the people that we want ... a responsible change in Costa Rica," a chasten Araya told reporters.

Chinchilla is leaving office as Costa Rica's least popular president in 20 years.

Earlier in the day Araya appeared certain that he would win 40 percent of the vote, the minimum needed to avoid a second round.

If Solis wins the April 6 run-off, it would be the first time in 50 years that a member of neither of the two leading parties -- the PLN or the Social Christian party (PUSC) -- is in power.

"I came to vote with the hope that there is change," said housewife Iris Rodriguez, 45, who called on the next government to "think a little about the poor."

The next president, who will take office on May 8, will have to deal with a split congress and will need to be a skilled negotiator, said sociologist Manuel Rojas.

"He will not be able to govern only with his party as has been done in the past," Rojas told AFP.