President Cristina Fernandez was re-elected in a landslide, winning with the widest victory margin in Argentina's history after her government spread the wealth of a booming economy.
Ms Fernandez had 53% of the vote after 58% of the polling stations reported nationwide. Her nearest challenger got just 17%.
Interior Minister Florencio Randazzo predicted the president's share would rise as polls reported from her party's stronghold of densely populated Buenos Aires province.
"Count on me to continue pursuing the project," Ms Fernandez vowed in her victory speech. "All I want is to keep collaborating ... to keep Argentina growing. I want to keep changing history."
Ms Fernandez is Latin America's first woman to be re-elected as president, but the victory was personally bitter sweet - the first without her husband and predecessor, Nestor Kirchner, who died of a heart attack last October 27.
"This is a strange night for me," she said, describing her mix of emotions.
"This man who transformed Argentina led us all and gave everything he had and more ... Without him, without his valour and courage, it would have been impossible to get to this point."
Thousands of jubilant, flag-waving people crowded into the capital's historic Plaza de Mayo to watch on a huge TV screen as she spoke from a hotel, where her supporters interrupted so frequently with their chants that she lectured them as a mother would her children: "The worst that people can be is small. In history, you always must be bigger still - more generous, more thoughtful, more thankful."
Then, she showed her teeth, vowing to protect Argentina from outside threats or special interests.
"This woman isn't moved by any interest. The only thing that moves her is profound love for the country. Of that I'm responsible," Ms Fernandez said.
Later, she appeared in the plaza as well, giving a rousing, second victory speech, her amplified voice echoing through the capital as she called on Argentina's youth to dedicate themselves to social projects nationwide.
Ms Fernandez was on track to win a larger share of votes than any president since Argentina's democracy was restored in 1983, when Raul Alfonsin was elected with 52%.
Her margin over Governor Hermes Binner and five other candidates was wider even than the 1973 victory margin of her strongman hero, Juan Domingo Peron.
Her political coalition also hoped to regain enough seats in Congress to form new alliances and regain the control it lost in 2009. At play were 130 seats in the lower house and 24 in the Senate.
Ms Fernandez suffered high negative ratings early in her presidency, but soared in popularity as a widow by softening her usually combative tone and proving her ability to command loyalty or respect from an unruly political elite.
Most voters polled beforehand said they wanted government stability to keep their financial situations improving in what has been one of Argentina's longest spells of economic growth in history.
Ms Fernandez, 58, chose her youthful, guitar-playing, long-haired economy minister, Amado Boudou, as her running mate.
Together, the pair championed Argentina's approach to the global financial crisis: nationalise private pensions and use central bank reserves to increase government spending rather than impose austerity measures, and force investors in foreign debt to suffer before ordinary citizens.
Argentina's world-record debt default in 2001 closed off most international lending, but it has kept the country booming ever since, with its economy expanding at twice the rate of Brazil's, economist Mark Weisbrot said.
The country faces tough challenges in 2012: Its commodities exports are vulnerable to a global recession, and economic growth is forecast to slow sharply in the coming year.
Declining revenues will make it harder to raise incomes to keep up with inflation. Argentina's central bank is under pressure to spend reserves to maintain the peso's value against the dollar, while also guarding against currency shocks that could threaten Argentina's all-important trade with Brazil.
Mr Boudou, 48, could now win attention as a potential successor to Ms Fernandez, but navigating these storms will require much skill and good fortune.
Opposition candidates blamed MS Fernandez for rising inflation and increasing crime and accused her of politically manipulating economic data and trying to use government power to quell media criticism.
Former President Eduardo Duhalde, who fell from front-running rival to near-last in the polls, said in a dour closing speech that "the country is dancing on the Titanic", failing to prepare Argentina for another global economic crisis.