SINCE taking over as director of Romania's National Anti-corruption Directorate (DNA) in 2013, Laura Codruta Kovesi has been prosecuting officials at ever-higher levels, putting a steady stream of former ministers and even an ex-prime minister behind bars. The DNA has become the poster child for the European Union's drive to tame corruption in its new eastern members, particularly Romania and Bulgaria. But it is safe to say that Ms Kovesi's latest target is her biggest yet. On June 5th, the DNA announced it is investigating Romania's sitting prime minister, Victor Ponta (pictured above), for forgery, money laundering, tax evasion and conflict of interest.

Romania's president, Klaus Iohannis, who was elected last December on an anti-corruption platform, promptly asked Mr Ponta to step down. The prime minister has refused. The DNA's charges are likely to touch off a struggle over new legislation to protect the powerful Mr Ponta, whose Social Democratic Party (PSD) is the largest in parliament. For the past few years Romania has been making progress in its struggle against corruption, but this latest battle will put that effort to the test.

Romania's Roma: the art of exclusion The 42-year-old Mr Ponta is a former prosecutor and a gifted politician who has managed to present himself as the incarnation of a young European generation, while at the same time protecting his party's established barons. The first set of charges against him stem from 2007-2008, when he was a lawyer in private practice. The DNA alleges that Mr Ponta was paid up to $3,000 per month in consultant fees (without performing any actual work) by another lawyer, Dan Sova. In 2011, when Mr Ponta had become a government minister and faced higher levels of scrutiny, he and Mr Sova allegedly forged documents purporting to show that Mr Ponta had done some work in exchange for the money Mr Sova paid him. The DNA's final charge, of conflict of interest, stems from more recent events: in 2012 Mr Ponta made Mr Sova a cabinet minister. Mr Sova was forced to step down as minister of transportation in 2014, when he became the target of a corruption investigation of his own (involving payments from a state-owned energy company). In a statement, the prime minister's office denied all of the DNA's charges. It also implied they had been unveiled in collusion with the political opposition. There is "a huge spin-doctoring campaign in the Romanian media to portray this as a political prosecution," says Cristian Ghinea of the Romanian Centre for European Policies, a think-tank. This is a bit of a throwback to the early days of Mr Ponta's political career, when he made campaign speeches attacking the DNA, which was investigating and jailing politicians from the PSD (and every other major party) and cutting off their sources of graft. He once compared the DNA's tactics to those of the securitate, the brutal secret police of the former communist dictator, Nicolae Ceausescu. In recent years Mr Ponta has given rhetorical support to the agency, in part due to pressure from the European Union and America to crack down on corruption. The DNA and Ms Kovesi herself have been demonised by businessmen and television magnates the agency is prosecuting, but Mr Ponta had not joined in the attacks. That may change now. The more serious threat is that Mr Ponta's attempts to save himself could cripple the entire anti-corruption campaign. Parliamentarians are debating laws "that essentially aim to destroy the criminal procedure code, rendering DNA’s efforts impossible," says Laura Stefan, who studies anti-corruption policy at Experts Forum, a Bucharest think-tank. The senate has passed a bill that would hamper preventive detention of suspects, widely used in corruption cases. Parliament has gone back and forth on whether or not it will lift the immunity of ministers and MPs from prosecution. (Last week the senate voted to preserve Mr Sova's immunity, prompting Mr Iohannis to say he could no longer work with the government.)

The political struggle over Mr Ponta's future will be bitter. Opposition parties introduced a motion Friday morning to censure the government. That motion will probably come up for a vote next week, even as parliament begins tangling with the question of whether to lift Mr Ponta's immunity. Alina Mungiu-Pippidi, a Romanian political scientist who chairs an EU corruption research centre, thinks Mr Ponta will try to turn his case into a constitutional crisis, pitting his allies in parliament against the courts and Mr Iohannis.

The European Commission stays officially neutral on judicial cases and political issues in its member states. But the Commission also monitors Romania's progress on corruption through its "compliance and verification mechanism" (CVM). Its most recent report in January said it is vital that the country start treating politicians as ordinary citizens before the law. The EU might try to exert subtle pressure on Mr Ponta to step down. Whether this would have any effect is an open question. In an interview in February, the prime minister, emphasising his commitment to the fight against corruption, told this newspaper that the end of immunity for MPs was a fait accompli. Instead, four months later, he is relying on it himself.