Rumours of another revolt from within President Pierre Nkurunziza’s regime reached a crescendo on Thursday when Second Vice-President Gervais Rufyikiri announced from Belgium that he had defected — a move that could pose a threat to his hold to power.

The vice-president, considered one of the last remaining moderates in the ruling party, had been sidelined by President Nkurunziza’s circle since March for opposing the president’s third term bid during a meeting of the CNDD-FDD council of elders.

Mr Rufyikiri, who holds Belgian citizenship, fled to Belgium from where he declared that he no longer supports President Nkurunziza and his party.

“The country is at great risk of collapsing and all partners withdrew and suspended their projects and funds due to your decision, you didn’t want to listen to what your fellow CNDD-FDD members advised you, instead expelling them from the party,” he said in his statement.

Analysts said the defection of such a senior official is a big blow to President Nkurunziza, who is fast losing key members to the movement opposed to his third-term bid.

It could also potentially plunge the country into a constitutional crisis and badly damage the president’s already sour relations with donors.

Mr Rufyikiri’s defection does bring constitutional problems for President Nkurunziza, who by law is required to share executive power with his two vice-presidents.

With the second vice-president out of office, the president cannot fully exercise executive powers — unless he appoints a new one, which would require recalling MPs and Senators who have to defend their seats on Monday.

According to article 107 of the country’s Constitution, the president can only issue decrees countersigned by the vice-presidents.

Except for ceremonial functions such as promulgating the Constitution or declaring wars, almost all major decisions must be arrived at through consensus between the president and his two vice-presidents, including appointing ministers or enacting new legislation or a policy instrument.

Article 122 of Burundi’s Constitution delineates duties between the two vice presidents, giving the first vice president “the co-ordination of the political and administrative domain” and the second vice president “the co-ordination of the economic and social domain.”

A source in Burundi familiar with the political actors who requested anonymity said, “It is quite possible the second vice president fled because he saw no future for himself in the current political line-up in the ruling party.”

The vice president announced his defection just hours before President of the National Assembly, Pie Ntavyohanyuma, left the country for Belgium on Wednesday night.

But authorities in Bujumbura have been quick to downplay rumours that he has also defected, saying he is out of the country for medical reasons, even as unconfirmed reports say that a former vice president and Member of Parliament Bernard Busokoza also fled the country on Wednesday night through the Gasenyi border into neighbouring Rwanda.

In April, Mr Ntavyohanyuma fell out of favour with the ruling party’s officials, almost getting impeached by CNDD-FDD for openly opposing President Nkurunzinza’s bid for another term.

The attempt hit a snag after the party failed to marshal 39 out of 71 votes required to remove the president of the national assembly.