In a dramatic escalation of Poland’s battle to restore rule of law, the police entered the country’s presidential palace on Tuesday evening and took two MPs into custody who had been hiding under the protection of President Andrzej Duda after being sentenced to prison terms for abuse of power.

The arrests cut to the heart of a fight between Duda and new Prime Minister Donald Tusk, who is seeking to unravel eight years of rule by the nationalist, conservative Law and Justice Party (PiS), rooting the previous administration’s loyalists out of key institutions like the media, courts and state-owned corporations.