By Candace Piette
BBC News, Buenos Aires
The Kirchners face a tough economic backdrop
Sunday's mid-term legislative elections seem set not only to change the composition of Congress but also act as a referendum on the presidential couple who have dominated Argentine politics for the past six years.
Cristina Fernandez, who succeeded her husband Nestor Kirchner as president in late 2007, has seen her popularity fall amid the country's worsening economic problems.
She brought forward the elections, which were originally set for October, arguing that this would then allow the country to unite to face the global economic crisis. The couple's critics said it was a ploy to scrape an election victory before the rot really set in.
"This is no ordinary election," Nestor Kirchner, who leads the governing Peronist party, told an election rally.
Pausing many times to allow the chants of his supporters to subside, he repeatedly reminded his audience of the advances made since he was elected president in 2003.
"Argentina has recovered. We have been able to build homes, create mortgages, renovate hospitals, there is now a good administration and we can now sustain ourselves in an economic crisis," he said.
Mr Kirchner faces his own tough race to win a congressional seat for the strategic and populous province of Buenos Aires and it is clear he is pulling out all the stops to retain Peronist control of the legislature.
ARGENTINE MID-TERM ELECTIONS
Brought forward from 25 October to 28 June
Half of the 256 Chamber of Deputies seats at stake: four-year term
Third of the 72-seat Senate being chosen: six-year term
When he took office, Argentina was facing economic and political near-collapse as a result of a massive debt default.
Argentines had seen a president chased through the streets by rioting mobs and seven subsequent presidents come and go.
But the world became hungry for Argentine grain and six years of economic growth averaging 8% followed - growth that Mr Kirchner and his wife benefited from.
But the political and economic landscape and outlook are now very different.
Opinion polls suggest the Peronists will lose their majority in the Chamber of Deputies, and possibly also the Senate.
Farmers say they have been affected by falling prices and drought
"If the government is not able to retain its majority in both chambers...Argentina will be in political chaos," said Aldo Abram, director of the Centre for the Investigation of Argentine Markets and Institutions in Buenos Aires.
"This will be seen as high risk and create more uncertainty. It could extend the recession well into 2011 and the flight of Argentine capital will continue," he added.
The elections are taking place not only amid deep economic problems, but also amid complaints of government incompetence.
Official figures, long contested, put inflation at around 5% while private analysts says the annual inflation rate is at least 15%.
Consumer spending has slumped, while crime and poverty have become increasingly visible problems.
Many Argentines have been shifting their savings into dollars and sending it offshore, unsure of the government's ability to deal with their economic woes.
A damaging row between the Kirchners and the country's powerful agriculture sector over taxation has also added to voters' concerns. Last year, President Fernandez nationalised the private pension system a move which horrified foreign investors.
But some analysts offer a more upbeat interpretation of the post-election future.
"There are strong concerns in Argentina about the political situation, you can see it in the flight of capital, " said Dante Sica, former industry minister and now an economic consultant.
"But after the elections, this uncertainty will go and there will be a kind of 'decompression' when people absorb what new alliances have been made in Congress. If the government puts through a few economic measures that are pending, confidence will return," said Mr Sica.
Much depends on the Kirchners' ability to form productive new political pacts. The opinion polls indicate the congressional vote is likely to be fragmented even within the governing Peronist party itself.
But Mr Sica suggests the ensuing discussions could create a healthier political environment after the elections with a government which has been used to no resistance at all being finally forced to consult Congress more.
And, according to Mr Sica, the pull of the presidential election in 2011 will also have a galvanising effect.
"The governing Peronist party will do everything needed to maintain power," he said.