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Michelle Bachelet's landslide presidential victory was the biggest in eight decades, yet turnout was the lowest since Chile's return to democracy, suggesting she'll lack a clear mandate to push for radical change when she begins her second turn in the office next year.

Bachelet, a moderate socialist, ended her 2006-10 presidency with 84 percent approval ratings despite failing to achieve any major changes. This time, Chilean leftists vow to hold her to her promises, which include a $15 billion spending program to overhaul education, improve health care and reduce the vast gap between rich and poor.

"The social and political conditions are here and at last the moment has arrived," Bachelet said in her victory speech after Sunday's election. "If I'm here it's because we believe that a Chile for everyone is necessary. It won't be easy, but when has it been easy to change the world?"

Chile is the world's top copper exporter, and its fast-growing economy, low unemployment and stable democracy are the envy of Latin America. But millions of Chileans who have protested in the streets in recent years say more of the copper wealth should be used to reduce income inequality and fix public schools.

Bachelet won 62 percent of the votes, easily defeating her conservative rival, Evelyn Matthei, who got only 37 percent in the worst performance by the right in two decades.

Bachelet needs momentum to overcome a slowing economy and congressional opposition. The general election in November gave her center-left New Majority coalition a slim majority in both houses, and she'll need the votes of center-right lawmakers to accomplish some of her proposals under Chile's complicated, multi-tiered congressional voting system.

For now, she has enough votes in Congress to pass tax increases and will likely get support for educational reform. Changing the Pinochet-era electoral system and constitution, however, require super-majorities.

"She'll achieve some things: The tax reform is in her pocket. ... I think student leaders who have been elected to Congress will sign off on educational reform. Bachelet's expectations are high, but things will be achieved," said Kenneth Bunker, a Chilean political scientist.

Patricio Navia, a Chilean political scientist at New York University, sees a tough road for Bachelet, who ran the U.N.'s women's agency after leaving the presidency.

"Her biggest challenge will be to match expectations with reality," Navia said. "She campaigned that the country was going to continue growing at 6 percent a year and it's barely going to grow at 3 percent a year. The expectations are much higher than what she'll be able to deliver."

This was Chile's first presidential election after voter registration became automatic, increasing the electorate from 8 million to 13.5 million of the country's nearly 17 million people. But voting became optional with the change, and only 5.5 million voted in the runoff — 41 percent.

"You can say that it's the most decisive victory in eight decades, but the most important thing is that Bachelet got fewer votes than her four predecessors, including herself in 2006," Navia said. "So the key here is that a majority of Chileans stayed at home, and there isn't really a big confidence vote for the reforms some people want to implement."

Many Chileans complain that policies imposed by Gen. Augusto Pinochet's 1973-90 dictatorship have kept wealth and power in few hands. Pinochet effectively ended land reform by selling off the nation's water, and he preserved the best educations for elites by ending central control and funding of public schools.

Although Chile has long been regarded as Latin America's most socially conservative country, opinion polls suggest inhibitions are eroding.

Divorce was illegal until 2004 and gay marriage and abortion are still not allowed. But Congress recently passed an anti-discrimination law after a gay man was murdered, and the pregnancy of an 11-year-old girl raped by her mother's partner triggered a national debate about abortion.

Bachelet has long supported same-sex marriage and abortion in cases of rape or risk to a woman's health, but hardly mentioned them during her first presidential race. She spoke out for both this campaign.

Chile's economy is regarded as the best-managed in Latin America, and Bachelet's proposals make some business leaders nervous.

Copper prices have plunged 30 percent since peaking two years ago, and Bachelet wants to raise corporate taxes 5 points to 25 percent. She approved dozens of coal-fired power plants and hydroelectric projects in her first term, but she now opposes them even though Chile needs more energy capacity.

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Associated Press writers Eva Vergara and Michael Warren contributed to this report.

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Luis Andres Henao: https://twitter.com/LuisAndresHenao