Ukraine ally Poland is moving to the political center. And that's bad news for Russia's Putin

• Victory for the Donald Tusk-led opposition "prevents the emergence of a populist Euroskeptic alliance in Central Europe" and will reset Ukraine relations, analysts and academics told CNBC.
• Poland would have remained Kyiv's ally on an overarching level but relations have become tense in recent months over a grain dispute and during the election campaign.

Poland's election result may not go down well in Moscow, as observers describe a victory for liberal centrism and an expected thawing of the country's frosty relations with both the EU and neighboring Ukraine.

The incumbent Law and Justice (PiS) party won the highest percentage of the vote in the electon held Sunday, with 35.4% — but opposition groups look set to form a parliamentary majority.

Donald Tusk — leader of the center-right Civic Platform party and the anti-PiS opposition's figurehead — positioned the vote as a chance to restore democratic norms and liberal values to the country, following eight years of nationalist, socially conservative rhetoric and policymaking.

"Moscow is unlikely to welcome a decisive victory of political parties with a strong pro-EU and pro-Ukraine stance," Andrius Tursa, Central and Eastern Europe advisor at consultancy Teneo, told CNBC.

While Russia focuses its attention on forging closer relationships with the likes of China and India, EU unity remains a thorn in Putin's side as the nations agree on more Russian sanctions and military and economic support packages for Ukraine in its conflict with Russia.

Poland has the European Union's fifth-largest economy and population, and has been an influential member since 2004. It plays a significant geopolitical role as a NATO base with around 10,000 U.S. troops stationed in the country. It has taken in more than a million refugees from its close ally Ukraine since the start of the war, with many more millions passing through it.

However, relations with the EU have become tense during eight years of PiS rule over Warsaw's near-total ban on abortion, and alleged chilling of media freedoms. The bloc has withheld billions in funding from Poland because of concerns over the erosion of judicial independence.

Its relations with Ukraine have soured in recent months, partly because of a dispute over the impact of Ukrainian grain imports on local farmers. Ukraine filed a complaint with the World Trade Organization over Polish restrictions on its produce, with the spat eventually resulting in Poland announcing it would no longer provide weapons to Ukraine.

Ukraine reset

As a former European Council president, Tusk is likely to target bringing Poland back into the EU fold, unlocking bloc funds and potentially making Poland less obstructionist on EU policy.

"From the regional perspective, the opposition's victory prevents the emergence of a populist Euroskeptic alliance in Central Europe (along with Hungary and Slovakia), which could have brought more internal tensions in the EU," Sili Tian, Europe analyst at the Economist Intelligence Unit, said in a note Monday.

Tian also expects the result to "reposition Poland as a staunch supporter of Ukraine" and for Tusk to push for EU accession for Ukraine.

The recent spat with the war-torn country was partly fueled by the election campaign, according to Aleks Szczerbiak, professor of politics and head of department at the University of Sussex.

"Law and Justice felt increasingly under pressure because its own polling was telling it that while its supporters were pro-Ukrainian, they felt there were issues where Polish and Ukrainian interests clash, where Polish interests needed to be stood up for," Szczerbiak said by phone.

That was exacerbated by the electoral threat from the far-right Confederation party, which accused Kyiv of not being sufficiently grateful for weapons sent previously, and vowed to curtail the passage of Ukrainian refugees. It has also broadly criticized the EU and Polish foreign policy approach to Ukraine during the war.

The Confederation party was previously seen as a potential kingmaker that Law and Justice could have partnered with to form a government, in a move that could have taken Poland even further to the right and antagonized its relationship with the EU. But the party significantly underperformed expectations, gaining 7.2% of the vote — close to what it achieved in the last election in 2019.

Strong foundation

The extent to which former Soviet satellite state Poland would have abandoned support for Ukraine even in the event of a different electoral outcome should not be overplayed, Szczerbiak noted.

"The big thing to bear in mind when looking at Poland and Ukraine is they have an overarching strategic common interest [challenging Russian aggression], and this supersedes everything. Whatever the ebbs and flows of the relationship, they will remain key allies in terms of the war," he said.

Poland would likely have remained a key hub for channeling humanitarian aid, supporting sanctions against Russia, and acting as a point for Ukrainian refugees to pass through and settle in, Szczerbiak said.

There is also part of the relationship that is outside of Poland's control, he added.

"There is a view in Poland that Ukraine is basically pivoting from forming close relations with Warsaw to prioritizing relations with Berlin — it has come to [the] conclusion pragmatically that if they want EU membership, the more important player will be Berlin. So it will be difficult to restore relations to how they were in the first 18 months of the war, regardless of what Poland does."

Rocky road ahead

Questions now linger over how quickly the opposition will be able to form a government, how much unity that administration will have and how much of its agenda it will be able to enact.

"It's one thing to agree to form a coalition, but it's another actually governing and having a coherent policy agenda when you've got three different groupings, all of which are made up of multiple groups within them, and they all have slightly or markedly different views about a range of issues," Stanley Bill, professor of Polish studies at the University of Cambridge, told CNBC by phone.

That disagreement is likely to span economic and social issues, including social spending and the liberalization of abortion laws.

Passing legislation may also face obstacles. Poland's president, Andrzej Duda, a PiS ally, holds veto power; and a Constitutional Tribunal stacked with PiS allies has the ability to strike down laws.

"The image of the president is of strong sympathy with PiS, but he does want to establish a somewhat independent position for himself and be a reasonable broker if there is strong social support for a policy," Bill said. "He's also had his criticisms of PiS, and vetoed some of their policies."