HELSINKI – Finnish Prime Minister Jyrki Katainen announced Saturday he was stepping down in June with a view to taking a senior European Union post, a move that could further unsettle a coalition government that last month lost one of its parties.

Katainen, who had led a quarrelsome six-party coalition government since 2011, said he would not run again as chairman of his conservative National Coalition party at its congress in June, which means he will then cease to be prime minister.

The surprise announcement means there is no clear front-runner to succeed him. Finnish media have floated the names of Economy Minister Jan Vapaavuori, Municipal Minister Henna Virkkunen, EU Minister Alexander Stubb or Petteri Orpo, who heads the party in parliament.

Katainen took the helm of National Coalition in 2004, taking the traditional conservative party in a more liberal direction and leading it to power in 2011 for the first time in 20 years.

He served as finance minister in the previous governing coalition and also as vice president of the European People’s Party, the biggest grouping in the European Parliament, until 2012.

The 42-year-old has been seen as a potential contender for top EU posts, although Finland’s tough stance toward bailouts in the eurozone crisis might make him unattractive to southern EU states.