Argentine President Cristina Fernandez de Kirchner looks set to win a second term in October after defeating her rivals in an open primary Sunday.

With nearly all the polling places reporting, President Fernandez had just over 50 percent of the vote, while her two closest rivals trailed by at least 37 percentage points. Voters chose from among Ms. Fernandez and nine challengers.

This was Argentina's first open primary, meaning that all parties put up a candidate and voters cast ballots for their favorite. Political analysts say the primary was more of a nationwide opinion poll than an election, and voters were responding to a booming economy, despite an inflation rate estimated at 25 percent.

The primary took place ahead of presidential elections on October 23.

Under Argentina's electoral system, a candidate who gets more than 45 percent of the vote wins the presidential election outright. Candidates can win the presidency in the first round with 40 percent of the vote as long as their nearest rival trails by at least 10 percent.

Ms. Fernandez was first elected in 2007, succeeding her husband, Nestor Kirchner, who died last year.