Cortizo, a 66-year-old businessman and cattle rancher, was 10 points clear of his closest challenger, former foreign minister Romulo Roux of the Democratic Change party, with polls showing independent Ricardo Lombana a close third.
Cattle rancher leads the way as Panama elects new president
Social-democrat Laurentino Cortizo is the favorite to win as 2.7 million Panamanians take to the polls on Sunday to elect a new president following a campaign dominated by talk of corruption.
Sunday's winner will succeed Juan Carlos Varela, who is unable to stand for re-election as Panama's constitution limits presidents to a single five-year term.
Corruption played a significant role in election campaigning in a country struggling to shed its image as a money-laundering paradise following the Panama Papers scandal three years ago.
Equally damaging was the admission by Brazilian construction giant Odebrecht that it had paid $59 million in bribes in Panama between 2010 and 2014 to secure major public works contracts.
Cortizo, a veteran politician and former agriculture minister known popularly as "Nito," said he wants to "rescue and transform Panama" and "leave a legacy" untainted by corruption.
"I'm leaning towards Nito Cortizo because of his ability, experience and knowledge, and I think he has all the tools and structure to carry out a large part of what he has proposed," Miguel Carrio, an insurance salesman, told AFP.
The surprise candidate in the race, lawyer and journalist Lombana, has surged in the polls on an anti-corruption ticket, garnering almost 20 percent of voter intentions, compared to Cortizo's 36 percent.
Lombana, a former Panamanian consul to Washington, has hit out at the traditional parties, a popular tactic at a time when public confidence in the political establishment has been hit by numerous scandals.
While he may be behind, 45-year-old Lombana could yet win Sunday's election, political scientist Harry Brown told AFP, given that "the context of corruption scandals favors independents."
'The country needs change'
Speaking to AFP, Dolores De Gracia said she would vote for Lombana "because in truth I'm looking for a change, this country needs a change. I trust him and I hope the corruption will end."
In recent days, Lombana has been boosted by public backing from singer Ruben Blades, a legend of salsa.
While Blades didn't mention Lombana by name, it was clear he was referring to the outsider candidate when he called on voters to pick an independent candidate promising constitutional reform in a bid to end corruption.
"If our country continues with these corrupt institutions, it will explode," said Blades, predicting that would lead to "violent reactions."
He is no political novice himself, having held the position of tourism minister from 2004-2009, while he unsuccessfully ran for president in 1994.
Roux, 54, is a former chairman of the Panama Canal Authority and has tried to appeal to Panamanians who have struggled with inequality and high living costs, as well as a health and welfare crisis, despite a growing economy.
In his campaign, Roux has been keen to point to the economic achievements under the now-jailed former president Ricardo Martinelli when he was foreign minister.
He has also managed to remain untainted by the multiple corruption accusations levied against Martinelli, president from 2009-2014, that have seen the 67-year-old jailed while awaiting trial.
In addition to the president, Panamanians will elect 71 deputies, 81 mayors and 700 local lawmakers.
It will be the sixth presidential election since the United States' 1989 invasion to overthrow the Manuel Noriega dictatorship.
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