Poland's diverse political landscape makes it difficult for parties to achieve majorities in elections. For that reason, Law and Justice's 39 percent is being regarded as a surprisingly strong signal. The ruling Civic Platform party won about 23 percent of the votes. If the results hold true, Beata Szydlo will become Poland's third female prime minister. But Jaroslaw Kaczynski — the twin brother of Lech Kaczynski, the president who died in a plane accident in 2010 — is believed to be the actual mastermind behind the party's success.
Jaroslaw Kaczynski took a decidedly anti-immigration stance in the days before the election, warning that migrants might carry dangerous diseases, the Associated Press reported. His party has also been skeptical of the European Union, which Poland joined more than a decade ago.
A few years ago, it seemed highly unlikely that a right-wing party would achieve a majority in Poland's parliament anytime soon. Europe should be prepared for similar surprises elsewhere.
Poland is still divided
Some of the party's success can be explained geographically: With the exception of areas around the capital, Warsaw, eastern Poland is generally poorer and has higher unemployment than the west. Law and Justice's support has been concentrated in the east, in the past and in Sunday's elections. In some eastern districts, more than 50 percent of voters decided to support the right-wing party, partly because they felt neglected by the ruling party.
Economics is not the only explanation for the geographical divide: "In the south-east, patriotism and religion have always been inter-twined," the Economist quoted an eastern Polish Law and Justice mayor as saying.
But the party's support is rising in the west
Centrist and left-wing parties in Poland, but also elsewhere in eastern and central Europe, should be concerned that people in so many areas voted for Law and Justice on Sunday. Although the level of support still differed widely between the east and west, many experts were surprised by the party's growing popularity in the west.
Despite its growing wealth, the Polish government has failed to meet basic needs of its citizens, according to a 2014 index. Whereas Germany and France had few problems ensuring nutrition and basic medical care, water and sanitation, shelters and personal safety, Poland lagged far behind.
Other data show that between 2001 and 2011, many Polish citizens left rural areas and moved to cities or even abroad. Poland is an exceptional case in that regard: There is no other country on the continent that has experienced a similarly striking flight from rural counties.
Despite being categorized as right wing, Law and Justice has some leftist economic goals that helped the party win over supporters in those areas: It wants to introduce a tax on bank assets, for instance. Working or middle-class citizens will supposedly receive more benefits in the coming years.
In the long term, however, that might backfire: "Faced with so many signs of a new, interventionist approach, investors may conclude that as Poland tilts towards nationalism, their best bet is to tilt away from Poland," Reuters columnist Dominic Elliott concluded.
How the new Polish government will affect European politics
In an interview with Britain's Financial Times newspaper, Michal Szuldrzyński, political editor of Rzeczpospolita, a leading Polish daily, said Monday that the party "wants Poland to be more sovereign in Europe, more independent in its politics, but also more effective, more successful."
That could have a particular impact on German Chancellor Angela Merkel's efforts to force other European countries to accept more refugees. Law and Justice has taken a staunchly anti-immigration stance. It is also not a big fan of the European Union in general and could prevent an agreement on a united climate-change policy.
Will voters in other countries follow?
Some of the reasons that led to the party's success could raise crucial questions for other countries.
Neighboring Germany, for instance, also has an east-west divide. Many, especially in the east, feel neglected by Merkel's conservative CDU government. Like in Poland, right-wing supporters in Germany complain about growing numbers of refugees and say that Germany's strong economy has not led to pay raises in the east, where average wages are still much lower than in the west.
Of course, Germany will not become a second Poland. Its economy is too strong and the country's east is too small population-wise. However, a party to the right of Germany's CDU has gained popularity in recent months: the Alternative for Germany party could become a focal point for those who feel neglected by more traditional conservative parties. That party could also force Merkel's CDU to adopt more extreme policy stances to avoid losing voters.
In France, the far-right National Front has made political gains in recent years. The party could benefit from the country's vulnerable economic situation and its problems assimilating immigrants.