MADRID: Spain's Socialists, struggling to regroup after a crushing November electoral defeat, are considering choosing a female leader for the first time in their history.

They meet this weekend to decide between ebullient 40-year-old ex-defence minister Carme Chacon and her rival, the wily, highly experienced former deputy premier, 60-year-old Alfredo Perez Rubalcaba.

If Chacon emerges victorious from the party congress being held from Friday to Sunday in the Andalusian capital of Seville, southern Spain, she will be the first woman to lead one of Spain's two main parties.

"It is a very open congress. It is really 50-50 because the two candidates have their arguments. Their speeches to the congress will be very important," said Anton Losada, political science professor at Santiago de Compostela University.

Attended by 972 delegates from the 17 regions of Spain as well as from the enclaves of Ceuta and Melilla in north Africa, the congress is to choose a successor to former prime minister Jose Luis Rodriguez Zapatero on Saturday.

The aim is to turn the party around after its November 20 election loss to the conservative Popular Party.

The Socialists have been hobbled by their record on the economy.

The unemployment rate shot to nearly 23 percent in the final quarter of 2011 and the public deficit is expected to come in at 8.0 percent of gross domestic product in 2011, well beyond the 6.0-percent target.

After conceding an outright parliamentary majority to Prime Minister Mariano Rajoy's Popular Party, the Socialists aim to adopt a programme that gives "an answer to the questions of our society in these times of crisis," party secretary Marcelino Iglesias said.

Of the more than 16,000 proposed amendments received for the congress, half were aimed at opening up and deepening democracy at the heart of the Socialist Party itself, the party secretary said.

Chacon wants to embody that revival even if, like her rival, she was part of the previous government.

In the elections she took a background role to Rubalcaba, who spearheaded the Socialists' campaign as the candidate for prime minister after Zapatero decided not to run again.

Now, Chacon, previously a lecturer in law, is building her profile with a series of meetings.

In a race that has been largely good-natured, neither candidate has shied from making digs at the other's expense.

Chacon argues the party must change, saying it had three warnings with the popular "indignant" protests, the loss of regional elections in May 2011 and then the general election loss, without mentioning that Rubalcaba led the party campaign. "We should not wait for a fourth warning," she says.

Rubalcaba has said Chacon's economic policy would be the "ruin" of Spain. In a television interview with Telecinco television he went further: "If I thought she was the solution at this time in the life of the party I would not have been a candidate, but I honestly don't think that."

At a farewell dinner with senior party members on Sunday, Zapatero reportedly asked the two candidates to avoid adding "unnecessary tensions" during the leadership battle.

Born in Catalonia, Chacon presents herself as keen, hardened, "anti-conformist", saying: "One thing the Socialist Party should not fear to fight is inaction."

She also claims support from the historic leftist bastion of Andalusia, and chose to launch her campaign from a village in the region, Olula del Rio, where her father was born.

Meanwhile Rubalcaba "relies on an image of safety. He can leverage a large part of the Socialist Party which thinks it is best to bet safe, to return to the Social-Democratic line, to stabilize the party," said Losada.

Even if he could not prevent the party's election debacle, Rubalcaba has a reputation as a tireless, courageous politician who gained popularity as interior minister with an unyielding opposition to armed Basque separatist group ETA, which has since declared an end to its armed struggle.

Importantly, Rubalcaba has won the declared support of Felipe Gonzalez, Spain's prime minister from 1982-1996.

The Popular Party will hold its own congress February 17-19, also in Seville, ahead of regional elections March 25 in Andalusia, which it hopes to wrest from the Socialists.