Gianni Pittella, leader of the Socialists & Democrats group in the European Parliament | Adem Altan/AFP via Getty Images ‘Lead candidate’ process for Commission president pick backed by European Socialists Spitzenkandidat process provides ‘genuine and direct voice’ for citizens, said Sergei Stanishev, leader of the Party of European Socialists.

Europe's main center-left political party reaffirmed its commitment Friday to selecting a "lead candidate" for Commission president in the 2019 European elections.

The decision, approved in a resolution by the Party of European Socialists at a convention in Lisbon, increases the likelihood that other major parties will similarly commit to the so-called Spitzenkandidat process, which is intended to make European elections more democratic and give voters greater input.

The process, first adopted for the 2014 elections, resulted in Jean-Claude Juncker, a former prime minister of Luxembourg being selected as the candidate of the center-right European People's Party (EPP), over his socialist rival, Martin Schulz, then a German member of the European Parliament.

According to the EU treaties, the Commission president must still be nominated by the European Council and elected by the Parliament. While the treaties call for the institutions to take account of the results of the European elections, the institutions are not required to favor the lead candidate of the party winning the most seats in the Parliament, meaning the Spitzenkandidat process is voluntary.

In its resolution Friday, the Party of European Socialists pledged to choose a common lead candidate and also to nominate that "candidate in an open, democratic and transparent process, exploring even the possibility of holding primaries."

In a statement the PES leader, Sergei Stanishev said: "We stand for democracy at home and abroad. We are determined to reinforce the Spitzenkandidat process so that citizens have a genuine and direct voice in choosing the next president of the European Commission."

Gianni Pittella, leader of the Socialists & Democrats group in the European Parliament said Saturday: "This unprecedented decision will tremendously reinforce the democracy and the citizens’ legitimization of the European Institutions."