Charles Mangion was yesterday appointed Leader of the Opposition in accordance with article 90 of the Constitution.
He was sworn in at San Anton Palace by President Eddie Fenech Adami.
Dr Mangion told the media he would be resigning the post as soon as the Labour Party elected its new leader and deputy leaders.
The post of Opposition Leader became vacant following the resignation of Alfred Sant, shortly before Dr Mangion's appointment. Three months ago, Dr Sant resigned from leader of the Labour Party after his party lost the third general election in a row.
The election for the new leader started yesterday and will continue this evening with the post now being battled by the oldest and youngest contenders, George Abela and Joseph Muscat, respectively, none of whom is a member of Parliament.
The Constitution lays down that "if there is one opposition party whose numerical strength in the House of Representatives is greater than the strength of any other opposition party, the member of the House who is the leader of that party" shall be appointed Opposition Leader by the President.
Dr Mangion will act as Leader of the Opposition until the appointment of a new leader. Unless the winner of today's election is co-opted to Parliament immediately, the party's new deputy leader for parliamentary affairs is expected to take over from Dr Mangion as Opposition Leader as soon as he is chosen following an election next Thursday.
Dr Mangion said yesterday that before taking on the post he contacted all the leadership contestants who all agreed he should proceed so that parliamentary work could continue. He said he had also informed all MPs of the situation. His appointment, he said, was temporary and created an interesting constitutional situation because, following Dr Sant's resignation, the President, supported by the Attorney General, saw it necessary to appoint a Leader of the Opposition.
Since the President believed he (Dr Mangion) enjoyed the majority support of opposition MPs, he acted in line with the Constitution to safeguard the parliamentary institution as he was in duty bound to do.