Presidential pre-candidates attend a primary election at a poll station, in Asuncion
Presidential pre-candidate for the Partido Colorado party Santiago Pena accompanied by his wife Leticia Ocampo, speaks to the media before casting his vote during the party's primary election at a poll station in Asuncion, Paraguay, December 18, 2022. Reuters

Paraguay's ruling Colorado Party - a conservative political machine that has dominated government in Asuncion for some eight decades - could be facing a major challenge at the ballot box next month.

Voters say they want change and are fed up with internal party squabbles and allegations of graft - opening up the door for a broad opposition alliance to win power.

The single-round election on April 30 will choose the president, legislators, and regional governors.

Opinion polls suggest the presidential contest will be a close battle between Colorado party economist Santiago Pena and lawyer Efrain Alegre from the opposition Concertacion Nacional, sitting well ahead of a large but fragmented field of opponents.

At stake are Paraguay's long diplomatic ties with Taiwan. Alegre has pledged to sever them in order to open up the country's major soy and beef export sectors to China.

Alegre has also promised to cut energy bills, launch more social welfare programs, and push judicial reforms. Pena, meanwhile, is pledging "employment reforms" to create more jobs and to toughen a fight on crime and drugs.

Since one-party rule in the 1950s, the Colorados have governed without interruption, except for Fernando Lugo's truncated 2008-2012 presidency that ended in impeachment.

Many voters say they feel it is time for something new.

"I want there to be change, I no longer wish to see the Colorados controlling everything," said Karina Galindo, a 50-year-old graphic designer in capital Asuncion.

"All the words they say in the campaign are empty for me because they promise anything."

Pena may also be impacted by a U.S.-led graft probe into Horacio Cartes, a former Colorado president who led the country from 2013 to 2018. Cartes, who denies the accusations, still runs the party and is Pena's main backer.

Among other internal divisions, current President Mario Abdo Benitez has given only lukewarm support to Pena, saying he is not the best candidate.

Meanwhile, Alegre's opposition party has done more to improve its appeal since a narrow defeat at the last election in 2018, said Marcos Perez Talia, a political science researcher at the University of Valencia.

"Now the Concertacion is a broader space for people coming together and there is more chance it will flip the vote," he said.

However, the Colorado party retains a powerful election campaign machine and supporter base that goes back generations. That could edge the result in its favor, said Marcello Lachi, a Paraguay-based political scientist.

Adelina Caceres, director of a public school in the town of Guarambare, on the outskirts of the capital, said she supported the Colorado party mainly because "her grandfather had been Colorado," and despite being often frustrated by them.

"I am always knocking on the doors of politicians to request help for the school... But we receive very little from the Colorados," she said.

Polls show Paraguayans are focused on jobs, security and corruption, and it may be the as yet undecided voters whose ballots will tip the balance on who takes power on Aug. 15.

"I think both parties are pretty awful," said Lorena Ruiz, a 45-year-old accountant. "I'm going to see before the elections who is a little more passable to receive my vote."