By Jeremy McDermott In Bogota

Horacio Serpa, Noemi Sanin, and Luis Eduardo Garzon are challenging the lead of Alvaro Uribe Velez in the race to become Colombia's next president. But who are the contenders?

Horacio Serpa

His trademark moustache now almost completely grey, Horacio Serpa is a grizzled veteran of the Colombian political scene and that is one of his great disadvantages.

For many of the electorate, the 59-year-old former interior minister and Liberal Party candidate represents the old-style partisan system that has cramped political space in Colombia for too long and generated a culture of corruption.

Horacio Serpa is a veteran of Colombian politics

Yet Mr Serpa's political history is impressive, starting in 1969 when he became mayor of the oil-producing city of Barrancabermeja.

But his more recent political memory is tainted by his association with the last Liberal President, Ernesto Samper, who was accused of accepting $6m for his 1994 campaign from the Cali drug cartel.

Both Mr Samper and Mr Serpa were exonerated of any wrong-doing by the Liberal-dominated Congress, but the United States was not convinced and revoked Mr Samper's visa.

Populist

Mr Serpa is aided by the well-oiled Liberal Party machinery, which has often been able to deliver the votes in more distant parts of the country.

His message and style is deeply populist, complete with quivering voice as he beats podiums across the country and makes much of his humble roots.

President Pastrana has failed to end the war

Yet his message of the need for a political solution to the country's civil conflict is stoking up little enthusiasm in a nation now tired of peace talks which have produced only the record levels of violence that Colombia suffers today.

Mr Serpa holds second place in the latest polls, with 31%, trailing the leader Alvaro Uribe by 17 points.

There is a fear that many Liberal voters will vote for Mr Uribe. Once a member of the Party, Mr Uribe campaigned for Mr Serpa in his failed 1998 bid to win the presidency. It was snatched from him by the narrowest margin by current President Andres Pastrana.

Noemi Sanin

Noemi Sanin rocked the Colombian political scene in 1998 when, standing as an independent, she managed to attract some three million votes - the first female and independent candidate to give the traditional parties a real run for their money.

The leading candidate Alvaro Uribe Velez has been the target of would-be assassins

A former member of the conservative party and foreign minister, Ms Sanin, at 53, still cuts a glamorous figure on the electoral trail, but has been unable to generate the same enthusiasm she aroused in 1998.

The main reason for this are the present circumstances where national security is the overriding campaign issue, not unemployment upon which she has focused.

'Too soft'

There is also the perception that, while clean and able, Ms Sanin is not the person to stand up to the warring factions and impose some sort of order in the anarchy that dominates all too much of the country.

Born into a middle class family of 15 children, Ms Sanin and her party "Yes Colombia" has support from differing sectors of the populace, but has only managed to poll 9% of the vote in the last survey, and is now fighting for third place with the left wing political aspirant, Luis Eduardo Garz�n.

Luis Eduardo Garzon

Running the most relaxed - and recently most advancing campaign - is the former trade union leader, Luis Eduardo Garzon, better known as "Lucho".

Mr Garzon is running a wide-ranging campaign

Whilst all the other candidates are most often seen in executive suits, Lucho still wears a polo neck and suede jacket and his campaign style is more at home in smoke-filled student halls, where he reasons and argues his case with quiet confidence and dry wit.

Whilst he only managed only 6% of the latest poll, Lucho's campaign is more significant than just statistics in that he is opening up Colombia's political left once more - too long the victim of assassination and oppression by right-wing paramilitaries and their drug lord allies, and tainted by association with Marxist guerrillas.

Open campaign

Born of a single mother, who he still lives with, the 51-year old Lucho has quickly become a national figure and, whilst not a serious presidential contender at the moment, has won a national prominence he could certainly build on.

He has attracted a broad spectrum of support, not just from traditional leftist bastions like the trade union movement from where he sprang, but from many independent politicians who won the greatest number of seats in March's congressional elections.

His current platform is too large and divided to ever hope to govern effectively but, by making space for the left wing, his campaign has revealed that Colombia's democracy, constricted and ailing, is still breathing.