LONDON – European right-wing populists are poised to deliver a blunt warning to mainstream political parties as they are predicted to make dramatic gains in the European Parliament elections starting on Thursday.

Voters in the 27 countries of the European Union (EU) are expected to elect the historical first right-leaning majority in the European Parliament for the next five years, in a sign of frustration with traditional political parties perceived to have failed to address the rampant migrant crisis and economic challenges facing the continent.

"It's a reflection, a frustration with what is happening in Europe," Alan Mendoza, the executive director of the London-based Henry Jackson Society, told Fox News Digital. "People are turning to the parties who have answers on this basis and who are standing up for these issues as far as some voters see it and saying that that's where they're going to cast their votes."

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Polls show populists are favored to receive a third of votes across the bloc, with hard-right political parties expected to finish on top in Austria, Belgium, the Czech Republic, France, Hungary, Italy, Netherlands, Poland and Slovakia, while making substantial gains in other member states, according to the European Council on Foreign Relations polling projections.

The previous term of the European Parliament was ruled by a broad coalition of the traditional center-right European People's Party, center-left Socialists and Democrats and liberals of Renew Europe. These parties are set to lose seats next week.

The right-wing populist block, consisting of hard-right Identity and Democracy and European Conservatives and Reformists groups, may hold a quarter of the total number of EU Parliament seats after the election, eclipsing the Renew Europe bloc and rivaling the leading pro-EU centrist parties. 

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Individual conservative members of the European People's Party will also find common ground with the new populist block on core issues, though the center-right party is unlikely to formally forge an alliance. Current European Commission President Ursula von der Leyen previously ruled out an alliance with the populist groups over their views about NATO, Ukraine and its Euroscepticism.

The surge in the popularity of the right-wing parties is propelled by the ongoing migrant crisis in Europe coupled with social and economic issues, as voters are increasingly dissatisfied with the political elite and view Europe as in decline.

"If you look at some of the policies that those on the far Left are pushing in the United States today -- whether its radical environmental policies shutting down family farms, reckless spending that is causing the cost of living to skyrocket for working families, socialized medicine, or our open borders agenda that is leading to mass illegal immigration, an uptick in crime, and strain on our economy -- all of these dangerous ideas have been influenced by Europe. It's essential we keep a watchful eye on what is happening in Brussels and stop these bad ideas overseas before they keep hurting us here at home," Matt Mowers, a former Trump State Department official and founding board member of the EU-U.S. Forum, told Fox News Digital.

"The data coming out of Europe is exciting because it suggests major gains could be made by conservatives in the European Parliament, which could push it to the right. This could finally force the EU to start treating European citizens as members of individual nations with self-interests rather than pawns in the schemes of the global Left-wing elite," he said. 

Mainstream political parties sought to outflank the rising populist tide last December when the European Parliament announced a "historic" migrant deal aimed at curbing the inflow of asylum seekers. The agreement, however, did little to change the perception of the EU's failure to deal with the crisis.

"The sense that Europe's borders are totally permeable and the perception that Europe's elite want migrants to come in is having an effect. As far as ordinary Europeans are concerned, this pressures public services such as housing, medical services, job opportunities," Mendoza said. "It reflects a broader acknowledgment that Europe's best years could be behind it," leading to voters embracing parties that they "might not have considered voting for 10-20 years ago."

The expected gains of populist parties in the European Parliament elections follow a string of domestic electoral successes by Italian Prime Minister Giorgia Meloni and the surprise victory of Dutch politician Geert Wilders’ political party in last year's domestic elections, and the strong showing by Marine Le Pen in the 2022 French presidential election where she forced a runoff with eventual winner, Emmanuel Macron.

Despite the likely right-leaning majority in the European Parliament, due to the institution's limited powers, it may not lead to immediate changes, but it will put the traditional political parties "on notice" to change course and adopt the populists’ policies.

"We're not going to see immediate shifts of dramatic policy within the Parliament or even beyond the parliament," said Mendoza, but stressed that the Parliament will play a pivotal role in electing the next European Commission president, who will have to appease the populist block on issues of migration.

"But it puts the mainstream political parts of Europe on notice that if they have no answers and continue to come up with no answers, or even worse, if they continue the failed policies that have led us to this position, then they will be punished even more so at the next election," he added. 

"If they decide to second the agenda, then we would expect to see a far greater shift in terms of Europe's policies, occurring quite quickly because the mainstream has taken on board people's complaints and decided to do things differently."

Mowers concluded, "Hopefully, the statement European citizens make at the polls in the coming days will spur momentum for the conservative movement in the United States as we approach our own elections in November."

The Associated Press contributed to this report.