Nearly 19 years in power, the veteran eurozone dealmaker took the largest share of the vote, although his centre-right CSV party lost three seats in the 60-member parliament.

Grand Duke Henri, the head of the European Union’s wealthiest per capita country, left the 58-year-old Juncker in caretaker control days before a summit with EU peers, pending talks with the main party leaders set for Tuesday.

A formal mandate to try and form a workable government is expected by Wednesday.

The electoral arithmetic means Juncker could be forced out if Liberal, Socialist and Green lawmakers concoct a three-way deal to try and govern on a two-seat majority.

However, allies in the conservative European People’s Party (EPP), that includes German Chancellor Angela Merkel, confidently congratulated Juncker.

“The people of Luxembourg have renewed their trust in Prime Minister Juncker and have given him the mandate to lead the country for another term,” said the grouping’s leader in the European Parliament, Joseph Daul.

Juncker’s Christian Social People’s Party (CSV) has won every election bar one since it was established in 1944.

The CSV secured 33.7 percent of the vote, down more than four percentage points on 2009 polls, taking 23 seats.

Official figures showed the Socialists in second place on 20.3 percent but the Liberals were widely seen as the big winners with a sharply improved 18.2 percent.

Each of these parties won 13 seats, with the Greens taking six, down one.

The 40-year-old head of the Liberal Party, Luxembourg city mayor Xavier Bettel, was labelled as the country’s emerging “kingmaker” by RTL Radio Letzebuerg.

Juncker congratulated Bettel’s party on its score, but insisted of his party’s desire to retain the keys to the Grand Duchy: “We claim priority”.

On the campaign trail, Juncker said he would be prepared to govern in a two-way coalition with either the Socialists or the Liberals.

The election had been brought forward by seven months after the discovery of misconduct in Luxembourg’s pint-sized secret services.

Juncker’s former coalition with the Socialist party splintered over misdemeanours from illegal phone tapping to dodgy dealing in luxury cars.

However, Socialist leader and outgoing economy minister Etienne Schneider, contesting his first general election in charge of his party, failed to convince.

An editorial in the Quotidien daily said he had not made the breakthrough the left had hoped for amid rising unemployment of up to nearly seven percent.

Juncker, who has spent nearly half his life in government, told AFP he did not “rule out” the possibility that a coalition could be formed against him in this AAA-rated, high-earning and low-tax haven wedged between Germany, France and Belgium.

Asked about coalition permutations, Bettel said: “We will see where we can achieve the greatest part of our goals — it’s not ‘with whom’ but how and what that counts.”