First ladies fight it out for Evita's legacy to secure a seat in senate

But that is about all Cristina Fernandez Kirchner and Hilda Gonzalez Duhalde would admit having in common. On Sunday, voters will decide which should be senator from the province around Buenos Aires. So voters will take sides in a feud that is splintering the Peronista movement and may determine the direction of Argentina for years.

Ms Fernandez, the glamorous wife of the President, Nestor Kirchner, characterises her opponent as the public face of crooks. The plainer Ms Gonzalez, wife of the previous president, Eduardo Duhalde, calls the Kirchners "traitors" to the Peronista cause.

In a country poised awkwardly between old-fashioned machismo and an unprecedentedly strong showing of women in politics, much of the media coverage has focused on Ms Fernandez's designer wardrobe, jewellery and make-up, the insinuation being that anyone so carefully groomed could not possibly be a true tribune of the people in the Peronist tradition.

"What would Evita do?" has been the question hanging over the campaign, and the answer has depended entirely on the crowd being asked it.

The showdown between the two women is especially bitter because they used to be allies. The Duhaldes have run a mighty political machine from Buenos Aires for years, and used it in the 2003 presidential election to back Mr Kirchner. Without them, Mr Kirchner - then a little-known governor from a remote southern province - would not have stood a chance. As it was, he only narrowly qualified for a second round of voting, which never happened because his adversary, Carlos Menem, withdrew first.

But since 2003, Mr Kirchner has had a run of good luck with the economy - still recovering from a near-collapse in 2001-02 - and earned widespread admiration for his willingness to play a tough game with Argentina's creditors at the International Monetary Fund. Now he believes he can squash the Duhalde machine and take over himself.

The battle is reminiscent of the struggles that racked New York and Chicago in the early 20th century, with the Duhaldes representing machine politics and the Kirchners promising civic reform and an end to endemic corruption. Whether the Kirchners are sincere is open to doubt. Newspapers suggest both sides are flooding poorer areas with money and household goods - from fridges to mattresses and roofing materials - to get out the vote. One report claimed some goods are being distributed by the Ministry of Social Action, headed by the President's sister.

Still, the Kirchner campaign appears to be effective. Cristina Fernandez Kirchner is from 15 to 25 points ahead in polls. Ms Gonzalez Duhalde was forced into saying: "Of course I will be happy if I win, but I am taking part in the election for my ideals, not for results. I don't think anything big should be made of the result."

But it will take a lot more than one election result to smash the Duhalde machine. The President needs dozens more seats in parliament to stabilise his position.

The paradox of modern Argentinian politics is that although almost all politicians in power calls themselves Peronists, the movement has split into at least three factions. The Duhaldes hate the Kirchners, the Kirchners hate the Duhaldes, and Mr Menem, the former president, hates them all, vowing to take revenge in the 2007 presidential election for what he says was a "historic fraud" last time.