FUSAGASUGA, Colombia (Reuters) - Four years ago, when Colombia last held congressional elections, Carlos Antonio Lozada was dodging army bullets in jungle trenches as he and his Marxist rebel comrades battled a government offensive.

Julian Gallo, known as Carlos Antonio Lozada of the political party FARC, speaks during the closing of their campaign before legislative elections in Fusagasuga, Colombia March 3, 2018. REUTERS/Felipe Caicedo

Back then he wore camouflage fatigues emblazoned with the emblem of the Revolutionary Armed Forces of Colombia (FARC) - two crossed rifles over the nation’s red, blue and yellow flag.

Now, as a 56-year-old candidate for the Senate in Sunday’s elections, Lozada no longer brandishes an automatic assault rifle and the FARC emblem has become a red rose on a white background.

The Spanish-language acronym now stands for the Revolutionary Alternative Common Force, the political party the rebel group established after a peace deal was signed in 2016.

As Colombia adjusts to the end of Latin America’s longest-running armed conflict, the FARC is pitching its defense of the poor and other proposals to a traditionally conservative electorate, divided between those who accept its new role in politics and those who demand its leaders go to jail.

“We’re learning to go to public squares and seek massive support for our ideas with arguments and proposals,” Lozada told Reuters, speaking at the close of his campaign for Sunday’s vote.

From the stage in Fusagasuga, an agricultural town close to the capital, the former rebel commander outlined the FARC’s plans for social change to some 200 flag-waving supporters and the curious.

“This is what we bet on when we signed the (peace) agreements,” said Lozada, who served 39 years as a rebel fighter.

As part of the peace deal, the FARC will be guaranteed five seats each in the 108-member Senate and the 172-member lower house. But polls show it faces an uphill battle in the fight for open congressional seats.

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The FARC has also expressed concern about the safety of its candidates, after many were pelted on the campaign trail with tomatoes, bottles and eggs by angry protesters.

Patriotic Union, a political party founded by the FARC and Colombian Communist Party in the 1980s, was decimated by a campaign of violent attacks and assassinations blamed on right-wing death squads and drug lords.

The new FARC suffered a setback on Thursday when Rodrigo Londono, its candidate for the May 27 presidential race and known by his nom de guerre Timochenko, withdrew due to ill health. The party said it would not seek a replacement.

HEALTH, EDUCATION, CORRUPTION

Colombia’s five-decade conflict and subsequent peace accord dominated elections in 2014. Now, candidates are focusing on health, education, corruption, the economy and closing the chasm between rich and poor in the country of 50 million people.

Sunday’s ballot will include party primaries to select the candidates who will compete in May’s election to replace outgoing center-right President Juan Manuel Santos.

It is unclear if Londono’s exit from the race will help give a boost to Gustavo Petro, a prominent leftist and former member of the now-defunct socialist M-19 rebel movement.

But polls show Petro will almost certainly emerge as a candidate from Sunday’s primary and his political rise, after serving earlier as Bogota’s mayor, stands out as something of an example for the FARC.

The 57-year-old economist and former senator was granted amnesty after serving two years in jail for his involvement with the M-19 insurgency.

Supporters of Petro’s “Colombia Humana” party highlight his work to improve conditions for the poor. He has pledged to create a “social economy” at the service of the people and shift it away from oil toward agriculture. A strong showing in Sunday’s election will likely worry markets.

“If voter turnout for the left-wing primary is close to the center-right coalition’s primary, this could consolidate Petro’s bid for the presidency,” Citibank said in a note to investors. “A lukewarm turnout could lead Petro to lose steam.”

On the right, Ivan Duque, a young senator with backing from former President Alvaro Uribe, looks set to notch a win over Marta Lucia Ramirez, a former defense minister, in Sunday’s primary.

Duque, 41, of Uribe’s Democratic Center party, is a lawyer and senator who studied at Georgetown University before working at the Inter-American Development Bank and United Nations.

While some are concerned by his lack of political experience and say Uribe will pull the strings if he wins, investors welcome Duque’s pledges to streamline the tax code and levy companies depending on their size.