By Robert Plummer BBC Americas regional editor

Kirchner and Menem: Traditionalist versus reinventor

Voters will have to choose between Carlos Menem, who has already served two previous terms in the post, and Nestor Kirchner, a provincial governor.

Yet these two members of the same party have drastically different views of how Argentina should be run - and the reasons have much to do with the complex history of the Peronist movement itself.

After the economic chaos in Argentina destroyed the country's traditional two-party political system, it proved impossible for the governing Peronist party to close ranks behind a single presidential candidate.

But in the absence of any other strong political force, the party has proved adept at providing its own opposition.

A romantic mythology has grown up around Evita and Juan Peron

The contender who is most favoured by the current administration, Nestor Kirchner, is also the one who would be most welcomed by General Juan Peron himself.

Mr Kirchner's talk of social justice and greater state control over industry is a conscious attempt to invoke the populist and corporatist rhetoric of the man who dominated Argentine politics in the 1940s and 50s.

Policies vs. personalities

But Mr Kirchner's back-to-the-roots version of Peronism faces a strong challenge from the man who radically redesigned the party in later years - Carlos Menem.

During Mr Menem's decade in office from 1989 to 1999, he pursued policies that were completely at odds with the original Peronist programme, liberalising the Argentine economy and even privatising the very companies that were nationalised under Peron.