"The real challenge will be to find compromises among more than two big mainstream groups," Florian Hense, a euro zone economist at Berenberg, told CNBC via email.
However, he highlighted that despite the upcoming split in voting intentions, pro-European parties are likely to still have the biggest share in Parliament.
"Opinion polls still suggest a two-thirds majority for the mainstream parties," he said. "(And) even if the radicals have big plans for the EU, they lack both democratic support and a common position to deliver them."
However, not everyone shares this opinion.
A report from the European Council on Foreign Affairs said Tuesday that anti-European parties are on course to win a third of the seats and would "frustrate activity, undermine the security and defense of Europe, and ultimately sow discord that could destroy the EU over time."
The same think tank said that anti-European parties are likely to work together to undermine European cooperation, such as pushing for an end to sanctions on Russia.
"Overall there will be more political volatility and this will inevitably affect the quasi-automatic adoption of European Commission proposals," Alemanno said.
Generally speaking, the European Commission is in charge of proposing laws, which are then discussed and approved by every country's minister at European Council meetings. The European Parliament then votes on these proposals.
According to Alemanno, 95 percent of European Commission proposals are adopted by the European Parliament and the Council. Significantly more than the percentage passed by U.S. lawmakers, he added.
"We are going to witness a sort of Americanization of the European decision-making progress by having a less automatic adoption of proposals," Alemanno said.