Even before the votes were counted in this election to the European Parliament, it was clear that some of the biggest winners are Euroskeptic political parties throughout the continent. Elected on their promises to stop further centralization of the European Union, to devolve power back to member states and to cut EU bureaucracy, these new politicians will be a major force in Brussels with negative implications for the EU’s effectiveness and, therefore, for the United States. In this, the first election to the European Parliament since the Lisbon Treaty gave it a more prominent voice in shaping EU policies, the influx of Euroskeptic politicians could undermine Europe’s ability to tackle a number of critical issues. Some of these Euroskeptic politicians will take on a spoiler role (not unlike Tea Party politicians in the US Congress), seeking to block any issue they don’t fully support, rather than working out pragmatic compromises.

The new European Parliament may have more difficulty reaching consensus on the need to finance projects to promote economic growth and create jobs throughout the continent. It may be less able to promote energy integration across the EU a step for which the Russia-Ukraine crisis has highlighted the strategic imperative.

A more divided parliament also may further undercut the effectiveness of the European Union’s foreign policy, an area in which it already has struggled. Finally, the big positive agenda in transatlantic relations now – the Transatlantic Trade and Investment Partnership (TTIP) – also could suffer since it could become more difficult for the European Parliament –like the US Congress – to eventually ratify an agreement.

Combined, these implications of the vote are bad news for the EU and the US as they confront Russia’s aggressive behavior on Europe’s eastern flank. The fact that Russia has funded and supported far-right populist parties across Europe means that Moscow could now get a stronger voice in Brussels.

Erik Brattberg is a resident fellow at the Brent Scowcroft Center on International Security at the Atlantic Council in Washington, DC.