The extraordinary victory of the democratic opposition in Poland’s election raises the spectre of a looming constitutional crisis. Like Donald Trump in the United States or Jair Bolsonaro in Brazil, the right-wing populist Law and Justice (PiS) party may refuse to concede.

This isn’t just doom-and-gloom speculation. After the polls closed and the result was clear, PiS leader Jaroslaw Kaczynski greeted his supporters on Sunday night by declaring, ‘We have won the parliamentary election! The third in a row!’ What followed was even more ominous: Poland, Kaczynski warned, faced ‘days of fighting, or tensions of various sort’.

A series of recent developments in Warsaw increases the risk of a seemingly unthinkable escalation in the coming days and weeks. Five days before the election, Poland’s armed forces chief of staff and his operational commander resigned for undisclosed reasons. Staunch PiS loyalists of questionable competence swiftly replaced both.

General Piotr Pytel, a respected former head of military counterintelligence, openly admits that senior military officers ‘reckon with the prospect of PiS launching a coercive scenario in the event of the lost or inconclusive election’. And sources close to PiS have reportedly discussed the idea of another election in case of a defeat, using a Polish football term that translates as both ‘overtime’ and ‘do-over’.

This has become a common gambit among today’s right-wing populists. In December 2020, Trump and his former national security adviser, retired General Michael Flynn, discussed plans to deploy the military to re-run the 2020 US presidential election. The year before, Turkish ruler Recep Tayyip Erdogan ordered a do-over of the mayoral contest in Istanbul when the opposition candidate, Ekrem Imamoglu, prevailed by a mere 15,000 votes over Erdogan’s ally. Incredibly, Imamoglu triumphed again, more decisively, as Istanbul’s angry citizens returned to the polls.

After eight years of ruthlessly concentrating power, PiS has numerous tools to trigger a similar scenario, and the singularly brutal campaign can also give PiS hope for a different outcome than in Istanbul. Kaczynski, Poland’s de facto ruler, may conclude that the opposition is exhausted after a grotesquely unequal race in which the government had almost unlimited resources at its disposal. If so, he has almost certainly miscalculated, but his misjudgement may turn out to have grave consequences for the country.

In particular, PiS’s control of subservient courts and the presidency could tempt it to try nullifying the voters’ will. The election can formally be declared invalid by a PiS-created special chamber of the Supreme Court, staffed entirely by PiS-appointed judges. In addition, the Polish constitution gives President Andrzej Duda a significant role in nominating the new prime minister and the cabinet.

Although the constitution clearly requires the president to appoint the premier favoured by a parliamentary majority, Duda has repeatedly disregarded constitutional mandates. Specifically, at the outset of his first term in 2015, Duda famously refused to receive the oath of three judges of the Constitutional Court duly elected by the parliament, thereby preventing them from taking their seats on the bench.

Duda may try to repeat this manoeuvre and illegally decline to appoint opposition leader Donald Tusk of Civic Platform as prime minister. He could then claim that the lack of a duly appointed prime minister forces him to call for a new election.

Any attempt to thwart the transfer of power will surely provoke intense social unrest. And with the armed forces now seemingly controlled by PiS loyalists, widespread protests may provide a convenient justification for declaring a national emergency. In this case, the Polish constitution mandates rescheduling an election—potentially as far as six months later. In the meantime, a caretaker government appointed by Duda would govern without any parliamentary oversight.

For the European Union, as well as NATO, such an anti-democratic turn in Warsaw is a nightmare scenario. The notion that they represent a community of values would be deeply discredited.

But that doesn’t need to happen. The shock of an EU member’s government openly refusing to cede power may, at last, force Western capitals to act. And NATO’s military leaders, who know the Polish officer corps well, can quietly remind their counterparts how dangerous a PiS nullification of the election would be for Poland’s security.

For the EU, everything should be on the table, including a long-overdue reassessment of whether harsh bilateral measures akin to the 2000 sanctions against Austria are always counterproductive. Another option, which legal scholars have started to discuss, would be for the EU Council simply to refuse to seat undemocratically appointed ministers. This would not be based on the unworkable suspension process prescribed in Article 7 of the Treaty on European Union, but on a political decision rooted in Article 10, which requires all council members to be ‘democratically accountable either to their national Parliaments, or citizens’.

The best scenario for Poland and the EU would be for PiS leaders to resist their worst instincts and proceed with the orderly transfer of power. By signalling that any attempt to undermine the will of the people will cross all European and NATO red lines, Poland’s Western partners can help Duda, Poland’s military leaders and other more level-headed officials avoid a tragic mistake.