Former Argentine president Nestor Kirchner, the current president's husband and a leading contender to succeed her in next year's election, died from a heart attack today.
Mr Kirchner, who was 60, was credited by many Argentines with putting South America's number two economy back on its feet after a devastating 2001/02 economic crisis, but critics reviled his combative style and interventionist economic policies.
Argentine bond and stock prices rose on news of the death of the centre-left politician, who kept a firm hold on the reins of power even after his wife Cristina Fernandez was elected to succeed him in 2007.
His death raises uncertainty about the government's strategy for next year's election, and might encourage Ms Fernandez to seek a second consecutive term or take a more moderate line.
At the famous pink presidential palace, the blue-and-white national flag was flying at half-mast and supporters tied roses and messages to the railings, some reading "Thank you Nestor."
Mr Kirchner, who died in the southern city of El Calafate, was still a popular leader when he left the presidency. But his approval ratings have since fallen, dented by a messy dispute with the nation's farmers and leading media conglomerate Grupo Clarin.
A lawyer, Mr Kirchner started his political career in the Patagonian province of Santa Cruz, where he was governor for many years, and was elected president as a virtual unknown in 2003 on the ashes of the economic meltdown.
A member of the dominant Peronist party, he quickly built strong alliances and oversaw a strong economic recovery that won him solid backing. He would almost certainly have won a second term in 2007, but chose to make way for his wife.
Opponents of the presidential couple criticized Kirchner's tough political style and outspoken attacks on big business,
journalists and political rivals.
When farmers rebelled over a tax hike on soy exports in 2008, Mr Kirchner accused them of plotting a coup, and increased state control over the economy, nationalising several companies.
Financial markets never forgave the Kirchners for the tough 2005 renegotiation of some $100 billion in defaulted bonds, which saw creditors walk away with a steep discount.
Mr Kirchner focused on cementing political alliances at home to shore up his administration and that of his wife, but he was secretary general of South America's regional grouping Unasur and had close links with fellow Latin American leftists such as Venezuela's Hugo Chavez, who called his death "a huge loss".
Mr Chavez declared three days of national mourning and leaders including US president Barack Obama and Chilean president Sebastian Pinera sent messages of condolence.
Felipe Sola, an Argentine lawmaker who split from the government to join the ranks of a dissident Peronist party wing, called his rival Kirchner "a formidable fighter".
"I've criticised him and I've defended him, but I've always admired his ability and recognised him as a unique politician," Mr Sola said.
Mr Kirchner also won praise for his efforts to bring military leaders to trial for human rights crimes committed during the nation's 1976-1983 dictatorship, in which as many as 30,000 people were killed in a crackdown on dissent.
When his wife succeeded him, many commentators compared the power couple to another husband-and-wife political dynasty to dominate Argentine politics - former president Gen. Juan Domingo Peron and his famous wife Evita.
Although he never formally confirmed his candidacy, Kirchner was expected to run at the next presidential election in October 2011, but concerns over his health increased after he underwent arterial procedures in February and September.
His wife's government said Mr Kirchner was rushed to hospital in the early hours of today after suffering an apparent heart attack at the couple's weekend home in Patagonia. Ms Fernandez was with him when he was taken ill.
Investors disliked Mr Kirchner's unorthodox economic policies, such as price controls and export freezes to curb inflation. Those policies have largely continued during his wife's administration, and Argentine financial assets abroad rallied on news of his death.
Argentina's portion of the JP Morgan EMBI Plus sovereign bond index tightened 45 basis points to 536 basis points in morning trade, the tightest level in more than two years. The index overall was just 6 basis points tighter.
Argentina's financial markets were closed for the holiday.
Reuters