EL CHALTÉN, Argentina — Along a teeth-chattering road that cuts across southern Argentina, a bright blue billboard stood out against the vast Patagonian steppe. It announced that the Route 288 road project, which at the time cost around 572 million Argentine pesos, or about $119 million, would be completed in 2016.
Six years later, there is more gravel than pavement and the sound of crickets is louder than the rumble of car engines.
That road and other unfinished highways like it now threaten Argentina’s most powerful and well-known politician, whose leftist brand of politics has dominated the country for two decades.
On Tuesday, the verdict in the case of Cristina Fernández de Kirchner, Argentina’s former president and current vice president, is expected to be decided by a panel of three judges on charges of aggravated fraud and directing an “illicit association” that oversaw a kickbacks scheme tied to construction projects.
Mrs. Kirchner is accused of steering hundreds of millions of dollars of taxpayer-funded contracts to a business associate and family friend to build roads in this remote corner of Patagonia, on the tip of South America — projects that often went unfinished or went drastically over budget.
Federal prosecutors are seeking 12 years in prison for Mrs. Kirchner and to bar her from holding public office, though even if she is found guilty, she will be able to appeal the verdict and run in the meantime. Argentina’s next presidential elections are scheduled next year, though Mrs. Kirchner has not said whether she intends to run.
The trial is the latest blow for Mrs. Kirchner, who has been investigated on roughly a dozen charges, mostly related to corruption, though four cases have been dismissed and she has been acquitted in two others. But no investigation had ever made it to trial — until this one.
A conviction could deliver the most dramatic blow to her credibility yet and reinforce the difficulty she already faces appealing to a wider audience.
Mrs. Kirchner has spent 30 years in the public eye, including as a first lady, president and currently as a senator and the vice president. She is a deeply polarizing figure who has helped split Argentina between those who favor her and her leftist movement, called Kirchnerismo, and those who say she has helped ruin a country that has struggled, regardless of the government in power, with high inflation, poverty and failed economic policies.
She has repeatedly denied all charges and in final remarks to the panel of judges last week, she called the tribunal a “firing squad.”
“They slandered, lied and insulted me and our government,” she said.
She also claimed that the trial set the stage for the assassination attempt against her in September, when a man pushed through a demonstration outside her apartment in Buenos Aires, pointed a gun at her head and pulled the trigger, though the gun did not fire.
Two people have been charged with attempted homicide, and a third person is accused of helping them.
A guilty verdict against the vice president could feed either narrative, said Lucas Romero, a political scientist and director of the Buenos Aires public opinion firm Synopsis Consultants.
“Those who criticize her and have a negative image of her, well, they will confirm what they already suspected: She is guilty, she is corrupt,” he said. “And those who follow her, sympathize with her, those who have a very intense affection for her, they will say this confirms that they are persecuting her.”
That divide is clear in the Patagonian village of El Chaltén, where the population of 1,700 was meant to benefit from the unfinished road projects tied to Mrs. Kirchner’s case.
Dante Ardenghi, 65, a local doctor, said he believes that the media and opposition parties fabricated or exaggerated allegations against Mrs. Kirchner to bring down her political movement.
What they really believe, he said, is that leftist presidents “shouldn’t exist in South America.”
But Luis Ledesma, 59, a substitute high-school teacher, says he thinks the Kirchners were corrupt.
“Everyone who got close to or was allied in some way to the inner circle of these people became rich in a very short time,” he said. “We’re talking about secretaries, chauffeurs.”
Across Patagonia, the unfinished roads are taking their toll. Antonio Flauzino, a Brazilian motorbiker on a 3,300-mile trip through Argentina, fell off his bike on another unpaved highway. It was his first accident of his two-week trip.
“I had heard stories, people said this part was very hard,” he said. Motorcyclists call the stretch of gravel road “the cursed 73 kilometers” because of its condition and the high-speed winds in the region.
“But I didn’t think it would be this hard,” he said.
The purported kickbacks scheme that Mrs. Kirchner is accused of overseeing occurred in the province of Santa Cruz during the 12 years that the Kirchners were in the presidency: Mrs. Kirchner’s late husband, Néstor Kirchner, served from 2003 to 2007 and Mrs. Kirchner from 2007 to 2015.
Santa Cruz has always been their political stronghold: Mr. Kirchner was born in the capital, Rio Gallegos, and served as governor of the province between 1991 and 2003. His sister, Alicia Kirchner, is the governor today.
Twelve other people are also accused in the corruption case including Lázaro Báez, the Kirchner associate who received the roadworks contracts, and two former Kirchnerista government ministers who have been convicted in other corruption cases.
Mr. Báez is currently serving a 12-year sentence for money laundering in a separate case. One of the ministers, José López, a former public works secretary, was caught on video trying to stash duffel bags filled with $9 million in cash, Rolex watches and a semiautomatic rifle in a convent in 2016 in an unrelated case.
The focus of Mrs. Kirchner’s trial has largely been 51 roadworks contracts that were awarded to companies linked to Mr. Báez, who went from being a bank employee in Santa Cruz to forming a construction company in the days before Mr. Kirchner became president in 2003. The prosecution said that from 2003 to 2015 the alleged scheme defrauded the Argentine state of more than 5 billion pesos, or about $926 million, according to officials.
The contracts were often awarded at inflated prices, went over budget or granted other special considerations, according to the prosecution. Almost half of the road projects were never finished.
“These were systematic acts of corruption promoted and maintained by the highest political leaders in the country,” said Diego Luciani, the lead prosecutor, during his closing remarks earlier this year.
The evidence presented during the trial included WhatsApp messages between Mr. López, the ex-public works secretary, Mr. Báez and the president of one of his construction companies.
The prosecution said the messages revealed a plan to hide evidence in the waning days of the Kirchner administration in 2015, by delivering final payments on contracts to Mr. Báez, laying off his employees and abandoning roadworks projects.
Some messages include references to “La Señora” who had to “make decisions.” The prosecution contended that “La Señora” was a reference to Mrs. Kirchner, though she was never mentioned by name.
Even if convicted by this court, Mrs. Kirchner will not go to prison on Tuesday, said Andrés Gil Dominguez, an Argentine constitutional lawyer. She has multiple avenues of appeal still available and, as a sitting member of Congress, enjoys immunity from arrest. Even without an appeal, she would probably not serve prison time, since Argentina allows people over the age of 70 to serve out their sentence at home. Mrs. Kirchner is 69 years old.
Mrs. Kirchner’s supporters have already suggested that they would protest if she is convicted. “When they read out Cristina’s conviction, thousands of us have to go on the streets all over the country to bring it to an institutional standstill,” said Luis D’Elia, the head of an organization representing the unemployed, in a radio interview.
The vice president has faced several other judicial battles and has emerged victorious in some of them.
Last year, a court dismissed charges against her over accusations that she conspired to cover up Iran’s purported role in the 1994 bombing of a Jewish community center in Buenos Aires, which killed 85 people. The accusations against Mrs. Kirchner were first made in 2015 by a prosecutor, Alberto Nisman, who was found dead of a gunshot wound in his apartment days later.
His death was never solved, and the matter has been a source of frenzied speculation and political infighting ever since.
A separate case that accused her of defrauding the government through the dollar futures market was dismissed last year.
Ana Lankes reported from El Chaltén, Argentina, and Natalie Alcoba from Buenos Aires.