Argentines go to the polls on Sunday to pick their next president, officially marking the end of an era. For the last 12 years, the presidency has been shared by one couple — Cristina Fernández de Kirchner and her late husband, Néstor Kirchner — whose influence on the country has been so sweeping that they have their own political movement: Kirchnerismo.

But while Mrs. Kirchner, 62, is constitutionally barred from seeking a third consecutive term, she is not going quietly. After emerging as one ofArgentina’s strongest leaders in decades, she has sought to assert her lasting sway with a range of calculated moves in recent months.

Daniel Scioli, the candidate endorsed by Mrs. Kirchner, speaks about a continuity with her policies, while suggesting a few important tweaks, like improving strained ties with the United States and Argentina’s creditors.

Adding to the message that her course will be maintained, Carlos Zannini, her legal secretary, who is believed to be one of her closest advisers, was picked to be Mr. Scioli’s vice-presidential running mate.

Mrs. Kirchner also pushed through a new law that would require congressional approval to sell state-owned stakes in companies, chiefly a portfolio acquired when she nationalized pension funds in 2008.

Axel Kicillof, her economy minister, said the measure would ensure that any effort to privatize such holdings in the future would not be a “unilateral decision by the executive branch,” making it much harder to undo some of her most contentious decisions. Mrs. Kirchner herself proudly said that “nobody’s pen will now be enough” to dilute the role of the state.

Mrs. Kirchner, who has often been underestimated by her opponents, has also moved to place supporters in important positions in the central bank and across the judiciary. Beyond that, her son, Máximo Kirchner, and Mr. Kicillof, a rising star in her administration, are also running for Congress.

People in her government contend that her influence is here to stay.

With his three-day beard, abhorrence for neckties and an office stacked high with tomes on political philosophy, Ricardo Forster fits right into the high echelons of Mrs. Kirchner’s leftist government. He even has the lofty job title to prove it: secretary for strategic coordination of national thought.

“Conflict is the energy of democracy,” Mr. Forster, a 58-year-old professor of philosophy, said in an interview. He defended Mrs. Kirchner’s combative governing style while listing the highlights of the Kirchner presidencies, including the broad expansion of antipoverty programs, and the nationalization of pension funds and the country’s largest oil company.

Some might brush off Mrs. Kirchner’s recent maneuvering as a last grasp for clout, but her popularity at the end of her second contentious term is relatively strong. With Argentina’s economy posting modest growth this year, avoiding catastrophic predictions, her approval ratings are around 42 percent, well above those of Brazil’s president, Dilma Rousseff, and Chile’s president, Michelle Bachelet, both of whom are battling corruption scandals and economic slowdowns.

“I take my hat off to her,” said Silvia Ribé, 45, an actor who was drinking coffee with friends at Gargantúa, a bar and community theater here. “She didn’t care about losing favor abroad. She was determined to cut ties with the international system,” she added, referring to Mrs. Kirchner’s battles with the International Monetary Fund and a group of creditors in New York.

“There’s something hazy about the figure of Scioli,” Ms. Ribé continued, explaining that she was concerned he could veer too far from Mrs. Kirchner’s leftist path. “He might sink us into the mud,” she said. “We don’t know if Cristina is going to put a revolver against his head so that he does everything to the letter.”

Mr. Scioli, 58, a former powerboat racer who lost his right arm when his boat flipped in 1989, switched to politics in the 1990s. He won a seat in Congress as a supporter of Carlos Menem, a former president from a conservative wing of Peronism, the ideologically malleable movement that dominates Argentine politics four decades after the death of the three-time leader Juan Domingo Perón.

But not everything is lined up for the continued influence of Mrs. Kirchner, who succeeded her husband as president in 2007 and was re-elected in 2011. While her own leftist movement, Kirchnerismo, has emerged as the dominant faction within Peronism, political analysts question whether that will remain the case after she leaves office.

Mr. Scioli served as Nestor Kirchner’s vice president from 2003 to 2007, but as governor of Buenos Aires Province he has sometimes been at odds with Mrs. Kirchner and her supporters, who have viewed him as too close to corporate interests.

“His conflict with Cristina is inevitable,” said Rosendo Fraga, an Argentine political analyst, reflecting a preference here for using Mrs. Kirchner’s first name. He noted the expectation that she could try to run for president again in 2019, an ambition that could put her on a collision course with Mr. Scioli.

Mrs. Kirchner herself seems to be welcoming talk about a possible return. She recently met with the author of a line of graffiti, “Embrace me until Cristina returns,” images of which have been widely shared on social networks.

In a well-polished video on her Facebook page, Mrs. Kirchner is shown defiantly celebrating her policies. Mr. Scioli makes an appearance, too, as if reminding him and the electorate of who paved the way for his candidacy.

“If Scioli wins,” Mr. Fraga said, “this will be the most important political conflict of the next period, something that is already being insinuated.”

Looking forward to the end of a long stretch in which Mrs. Kirchner relished clashing with opponents in the news media and the business establishment, some Argentines cannot wait for the president and her polarizing style of governing to leave office.

“It’s the best thing that could happen to us,” said Juan Addesi, 52, a watch repairman. Mr. Addesi, who plans to vote for Nicolás del Caño, a socialist, said he was angry that his business had been hindered by import restrictions that make it difficult to obtain spare parts. “I could be 10 times better off,” he said.

Others question how Mrs. Kirchner, whose personal wealth has grown over the past decade, according to her sworn declarations, will handle claims of corruption once she leaves office.

She is under investigation over accusations that a family hotel business in Patagonia was used to launder money. A businessman with close ties to the Kirchners has been accused of paying for block reservations through his companies, but the rooms appeared to have never been occupied. Mrs. Kirchner’s chief of staff said the investigation had become a defamation campaign against her.

Claudio Bonadio, a judge leading the case, was removed from the inquiry this year after he ordered several raids on offices of the hotel business. Judge Daniel Rafecas, his replacement, is widely viewed as partial to the government. In 2012, he was removed from a corruption case involving the vice president, Amado Boudou, after sending WhatsApp messages advising Mr. Boudou’s lawyer. One of Mrs. Kirchner’s opponents warned this weekthat the inquiry into the hotel business could be shelved, an expectation echoed by others.

Still, Mrs. Kirchner is trying to project her sway beyond the elections, which could go to a second round if no candidate wins outright on Sunday.

“It’s the last kiss of power for her,” said Federico Finchelstein, an Argentine historian at the New School for Social Research in New York, noting that Mrs. Kirchner had held a teleconference recently with President Vladimir V. Putin of Russia, emphasizing plans to forge closer “strategic” ties between the two countries.

“She’s trying to assert the foreign policy of the next administration,” Mr. Finchelstein said. “But if history prevails, there will be an exodus to the new president. After all, he’s the one who controls the purse strings and effectively signs the checks from the executive branch.”

Mrs. Kirchner’s supporters say that much depends on the paths pursued by the president and her successor.

“She’s not going to interfere in any decision that Scioli takes,” said Mr. Forster, the secretary of national thought. Then he qualified that statement, adding, “unless there’s a dramatic shift in what this political project has consisted of until now.”