A Socialist single mother will face a conservative millionaire in a presidential runoff next month after failing to win an outright majority in her bid to become Chile's first female leader.

Michelle Bachelet easily defeated two feuding right-wing candidates with 46 percent of the vote, but fell shy of the 50 percent needed for victory. She is aligned with President Ricardo Lagos' ruling coalition that has governed Chile since the 1990 collapse of Gen. Augusto Pinochet's military dictatorship.

Opinion polls during the campaign have indicated Bachelet would likely triumph in any runoff scenario, making her Latin America's fourth elected female leader. But her opponents have vowed to join forces to defeat her.

Her closest rival, Sebastian Pinera, trailed with 25 percent of the vote, according to returns announced by the government. The third main candidate, economist Joaquin Lavin, got 23 percent.

On Sunday night, one of Bachelet's top aides, Jaime Mulet, played down concerns over the two right-wing candidates winning more combined votes.

"Their votes cannot be added. You don't add apples and pears," Mulet said.

Bachelet, who once was imprisoned by Chile's military dictatorship and went on to serve as defense minister, could pick up support from voters who backed the fourth-place finisher, who represented a coalition that includes the Communist Party. The runoff is Jan. 15.

Lagos, who cannot run for re-election, is ending his term with an approval rate of more than 70 percent. His successor will be sworn in on March 11 for a four-year term.

Lagos said his coalition won a majority in both houses of congress on Sunday, although no final results were available.

Both Bachelet and Pinera campaigned on promises to reduce the gap between the rich and the poor and curb an 8 percent unemployment rate and rising crime in large cities — with no major changes to the current economic model.

Chileans appeared to put the legacy of Pinochet behind them during the election. The 90-year-old former dictator played no role in the campaign. He wasn't even able to cast a vote Sunday, as he remained under house arrest, facing human rights and corruption charges.

Bachelet is the daughter of an air force general who opposed the Pinochet coup and was jailed and tortured by his peers and died in prison. Bachelet herself was also briefly jailed along with her mother. Both were blindfolded and mistreated in prison before being allowed to go into exile, first in Australia then in East Germany.

The candidate for the center-right National Renewal party, Pinera is unusual among Chilean conservatives, having openly opposed the Pinochet dictatorship. He has made inroads against Bachelet since entering the race in May with a platform aimed at the middle class and poor, including offers of pensions to housewives and incentives to small- and medium-sized enterprises.

Pinera has refused to discuss the value of his assets, but most estimates put them close to $1 billion. His companies range from finance and banking to Chile's largest airline and a television channel. He promises to put it all in a blind trust if elected president.

Bachelet on Sunday encouraged her supporters to redouble their efforts.

"Perhaps our message did not get through to voters," she said. "But that's a good reason for us to work harder."

Pinera struck an optimistic note: "Today we have taken a first step. On January 15th we will take the second step to start changing our country's history."