The Guardian view on Sri Lanka: president v prime minister

Most of us have regretted mistakes. Sri Lanka’s president, Maithripala Sirisena, is unusual in regretting what he got right. Three years ago, he led the diverse coalition that unseated the strongman Mahinda Rajapaksa, whose increasingly authoritarian leadership was undermining opposition parties, the judiciary and the media while his family and friends prospered. Mr Sirisena and his prime minister, Ranil Wickremesinghe, promised to curb executive powers and amended the constitution so that the president could not remove a prime minister unless they resigned or lost the confidence of parliament.

But the pair’s unhappy alliance has deteriorated to the point of no return. Last month, the president dismissed Mr Wickremesinghe, announced that he was replacing him with his old foe, Mr Rajapaksa, and suspended parliament until he could muster sufficient votes for the switch. That failed: many share his frustrations with the prime minister, but are much angrier at the president’s tactics. Mr Wickremesinghe has refused to go. This week the supreme court rejected the dissolution of parliament and calling of elections – the president’s fallback plan – and said it would give a final judgment next month. The reconvened parliament passed a vote of no confidence in Mr Rajapaksa, which the president rejected; a second vote ended in a brawl . The suspicion is that the president and his chosen prime minister hope to give the impression that Sri Lanka is becoming ungovernable and that fresh elections are the only solution. Mr Rajapaksa has already begun dishing out goodies such a cut in fuel prices. He is very popular though very divisive, accused of large-scale human rights abuses including in the bloody war with Tamil militants.

Mr Sirisena pledged to be a one-term president, but appears to have changed his mind and concluded that a partnership with Mr Rajapaksa is his best shot at hanging on to the job. This shows a touching faith in the loyalty of his erstwhile foe. He may believe that Mr Rajapaksa’s priority is the progress of cases against friends and relatives, including his brother Gotabaya, due to stand trial shortly. Others think Mr Rajapaksa could use the premiership to overhaul the constitution so that he could stand again – or, worse, that Gotabaya, a feared former defence minister, might run.

A negotiated outcome is possible, though other figures from Mr Wickremesinghe’s United National party had rejected earlier offers to install them in his place, and the president’s brute tactics have backfired. If not, some fear that the violence in parliament could spill on to the streets, or that security forces might be encouraged to step in. Mr Sirisena appears to have been taken aback by the reaction from the international community (though China congratulated Mr Rajapaksa). That pressure must be sustained. It would also be useful for the US and Britain, who support military and police training, to stress to security forces that this constitutional crisis must be resolved by constitutional means. The strong stance of MPs and the supreme court is welcome. They need support.