THE melodrama that is Peruvian politics has just taken another unexpected turn. On October 3rd the country’s supreme court revoked a pardon granted last December to Alberto Fujimori, an 80-year-old former strongman who was president from 1990 to 2000. That decision adds an unpredictable factor to a confrontation between Peru’s current president, Martín Vizcarra, and the largest party in congress, Popular Force (FP), which is led by Mr Fujimori’s daughter, Keiko.

Mr Fujimori was convicted in 2009 for his role in the murder of 25 people in the early 1990s by government-backed death squads. He was sentenced to 25 years in jail. In December last year the then-president, Pedro Pablo Kuczynski, pardoned him, ostensibly on health grounds. But it happened just as Popular Force was threatening to impeach Mr Kuczynski, so most Peruvians concluded that he freed the former president to placate Mr Fujimori’s daughter. Mr Kuczynski resigned in March this year.

In a 222-page ruling, a supreme-court judge, Hugo Núñez, said Mr Fujimori was ineligible for parole and ordered his arrest. (The Inter-American Court of Human Rights ruled in June that Peru’s courts had to make a decision by the end of October or it would do so for them.) The former president immediately headed to a clinic, outside which his supporters held a vigil. He is appealing against the decision in the constitutional court. Although Mr Fujimori was an authoritarian who dissolved congress and tolerated rampant corruption, many Peruvians credit him with defeating Shining Path, a vicious guerrilla group, and ending hyperinflation.

Mr Vizcarra, who succeeded Mr Kuczynski as president, has set out to dismantle much of what Mr Fujimori created. In July he announced that he would submit legislation for a referendum to approve reforms of politics and the judiciary. The reforms are in part a response to a scandal that has engulfed the justice system. The changes include a return to a bicameral congress, which would replace the one-chamber body that Mr Fujimori introduced when he reopened the legislature. Another measure would reform a panel that appoints judges, which Mr Fujimori created in 1995. Mr Vizcarra also wants to clean up campaign finance and end re-election for legislators.

This has brought him into conflict with Ms Fujimori, the ex-president’s daughter, who calls the referendum a ruse by Mr Vizcarra to hide the incompetence of his government. The president doubts that congress woud act without one. It has been talking about a bicameral legislature for a decade.

Until now Ms Fujimori has been on the losing end of the argument, in part because her family, and thus her party, is split. She has broken with her brother, Kenji, who is Mr Fujimori’s youngest child. Mr Vizcarra is also much more popular than the former First Daughter. In a survey published on October 1st by Datum, a polling firm, the president’s approval rating was 61%, 14 percentage points higher than a month before. Ms Fujimori’s rating dropped for the fourth consecutive month, to 11%.

Mr Vizcarra has capitalised on this. When congress sought to delay discussion of his reforms he called for a vote of confidence in his cabinet. Ms Fujimori likened the manoeuvre to a coup, but Mr Vizcarra won the vote handily on September 19th. More than half of FP backed him. Congress has now approved the four questions that Mr Vizcarra wants to put on the referendum ballot. The referendum is tentatively scheduled for December 9th.

The reincarceration of Mr Fujimori, if it happens, could change the mood. Immediately after Mr Núñez’s decision, the FP called a press conference, pledging a united front. Kenji accompanied his father to the clinic, tweeting that he felt “immense sorrow”. His sister wept. A wave of sympathy for the ageing authoritarian could boost FP’s standing in the polls. A first test will come on October 7th, when 23.4m Peruvians are legally obliged to vote in state and local elections. FP has a chance of winning some governorships.

The next trial of strength could be the referendum itself. It is not yet clear whether the FP will campaign for a No vote. Even united and energised, the Fujimori clan would probably not be able to defeat the reforms championed by a popular president. The question is whether the overturning of Mr Fujimori’s pardon marks the beginning of a comeback for a weakened political force.