Laura Chinchilla (C) who won 47 percent of the vote, with supporters Sunday after voting in San José.

MEXICO CITY: Costa Ricans elected a former vice president, Laura Chinchilla, as the country’s first female president, giving the ruling party a resounding victory.

Ms. Chinchilla, 50, won 47 percent of the vote, and both the second- and third-place candidates, the leftist Ottón Solís and the libertarian Otto Guevara, conceded before 10 p.m. Sunday.

Ms. Chinchilla thanked her supporters through Twitter before heading to a hotel in the capital, San José, to deliver her victory speech.

The dominant theme of the campaign was voters’ concerns over rising crime, and Ms. Chinchilla, a former minister of justice, has promised to raise spending on security by 50 percent. Speaking to the crowd, she said: “The greatest challenge we have is crime, violence and drug trafficking. I have said it in a dramatic way: Central America could be the last battlefield of the war taking place in Colombia and Mexico.” She added, “We must recuperate our tranquillity.”

Ms. Chinchilla, of the National Liberation Party, promised continuity with the free-trade policies of out-going President Óscar Arias, a winner of the Nobel Peace Prize who helped guide Central America out of its cold war conflicts.

Although she follows the center-left welfare policies of her party, she is social conservative who opposes abortion and gay marriage. Ms. Chinchilla holds a master’s degree in public policy from Georgetown University and is the mother of a teenage boy.

As the early results were announced, Ms. Chinchilla’s supporters began to fill the streets of the capital, waving the party’s green and white flag.

Although Costa Rica is still a relative oasis of peace and economic development in Central America, the rising crime rate there became the dominant issue in the campaign. Ms. Chinchilla blamed organized crime and the spillover from drug trafficking through Central America.

The global economic crisis pushed Costa Rica into recession last year, but the economy is expected to grow this year.

Both of Ms. Chinchilla’s leading opponents had argued that if she won, Mr. Arias, who is 69, would continue to wield power from behind the scenes. A campaign commercial for Mr. Solís showed Mr. Arias pulling the strings on a marionette representing Ms. Chinchilla.

The campaign has had its share of unusual moments. In response to questions over campaign financing, Mr. Guevara took a polygraph test on television. Mr. Solís also submitted to a test, but Ms. Chinchilla declined.

Laura Chinchilla celebrates victory with her supports