THE European Union (EU) faces a decisive week as incoming chief executive Jean-Claude Juncker seeks approval for his new team to start tackling the economic and foreign policy challenges that beset the continent.

With the eurozone on the verge of a new crisis, the risk of spillover from turmoil in the Middle East, and relations with Russia still tense over Ukraine, Europe is under pressure from all sides to act.

But Brussels is in limbo until Juncker's new European Commission (EC) replaces the outgoing team, led by Jose Manuel Barroso, as the executive arm for the bloc of 28 nations and 500 million people.

The European Parliament is due to vote in Strasbourg on Wednesday on Juncker's commission in its entirety. If it passes, Juncker's team can start its five-year mandate as planned on November 1.

The EC is arguably the most powerful institution heres, as it drafts laws and policies for a sprawling region that, taken together, represents the world's largest economy.

But that depends on the last two members of Juncker's team - including the controversial Slovenian candidate Violeta Bulc, named at short notice after Parliament rejected her predecessor - passing interviews with Parliament today.

"It's not a done deal, but it's likely" Parliament will vote as planned, said a source.

A source in Juncker's centre-right European People's Party added that there was a "95 percent chance of a vote on Wednesday".

If the vote is delayed, it would cast a shadow over a summit of European leaders here on Thursday and Friday, during which they are supposed to rubber stamp the new commission.

The summit agenda is already difficult, with leaders facing tough talks on climate change targets for 2030, plus calls to do more to tackle the Ebola outbreak in Africa and militant groups in Iraq and Syria.

But it would also leave Barroso's commission as a lame-duck administration at a time of crisis, with the possibility that it could take until January or February before Juncker's team is pushed through, EU sources said.

Barroso's two previous commissions in 2004 and 2010 both took office late after commissioners were rejected.

World stocks plunged last week on fears of a triple dip recession in a stagnant eurozone economy that is flirting with deflation, and new worries about Greece.

Juncker's flagship plan for his first months in office is a €300 billion (RM1.3 trillion) investment package to boost jobs and growth, and any delay would be a further blow to the eurozone.

The commission also faces an early test from the review it must carry out of budgets submitted by France and Italy that challenge the EU's strict fiscal rules imposed after the eurozone crisis.

Meanwhile, any delay in approving the commission could also revive doubts about the "democratic deficit" in the EU, with increasingly alienated European voters watching Brussels tearing itself apart.

Slovenia's Bulc, a deputy premier and telecommunications entrepreneur, will be interviewed today for the post of transport commissioner. AFP