But the paradox is that the powerful senator’s strongest asset as she embarks on what the government still hopes, in spite of bitter defeats in provincial and city polls, will be an easy path to victory in elections in October, is her husband.

For many Argentines, shell-shocked by the country’s 2001-02 economic crash in which their savings were confiscated and their currency savagely devalued, President Néstor Kirchner’s four years in power have been a soaring success.

Spectacular growth of more than 8 per cent each year has driven a wave of consumer spending, and in spite of a deepening energy crisis and worrying inflation, the strength of the economy is still likely to count most at the ballot box.

Voters know that in spite of differences in approach – Ms Fernández is considered somewhat more open, conciliatory and market-friendly than her husband – the two are, like their US counterparts Bill and Hillary Clinton, very much cut from the same cloth.

“They are a team and they have a common project,” one businessman who has known the couple since the early 1990s said of their political double act.

Mr Kirchner runs the country like a king from his court in the “pink palace” in Buenos Aires, and for months had been flirting openly with the kind of abdication in favour of the candidacy of his wife that would be unthinkable in many parts of the world.

Ms Fernández, meanwhile, behaves as if she were already on the campaign trail, meeting heads of state and business leaders on a whirl of international tours.

Opinion polls have consistently shown either capable of a first-round victory in October, although four months is a long time in Argentina’s turbulent political scene. However, recent election defeats of allies have suddenly made the government look less invincible.

Ms Fernández, who is due to launch her candidacy formally at a rally on July 19, would not be Argentina’s first female president: Isabel Perón succeeded her husband, President Juan Perón, on his death in 1974 before being toppled in a coup.

Unlike Evita, Gen Perón’s previous wife and Argentina’s most famous political consort, Ms Fernández has a parallel career to that of her husband (see box), and she certainly does not see herself as his puppet.

“She is very hard working, very focused, very cultured,” said Fernando Braga Menendez, the publicist for Mr Kirchner’s 2003 presidential campaign. “But she has a defect: she doesn’t suffer fools gladly.”

She also lacks her husband’s passion for economics – a potential problem given the monetary and fiscal challenges she may face as president. Mr Kirchner’s price controls have failed to staunch inflation and severe energy shortages are making unpopular rises in fuel and utilities prices increasingly urgent.

If Argentina wants to return to international capital markets, Ms Fernández as president would also have to negotiate with the holders of $20bn (€15bn, £10bn) in defaulted debt who refused the government’s 2005 restructuring. However, the substance of her government would be unlikely to diverge much from Mr Kirchner’s recipe of state intervention, especially since he is expected to retain influence.

Mark Jones, an associate professor of political science at Rice University in Houston and an adviser to the US government on Argentina, saw Ms Fernández as a head of state with Mr Kirchner a behind-the-scenes premier.

However, Peter Hakim, the president of the Inter-American Dialogue, a Washington think-tank, said: “It’s unclear whether Cristina will be happy in being a surrogate or whether she would use [the presidency] as an opportunity to show that she is the stronger, better, more capable of the two.”