As the tussle continues, here’s a look at the key players and the developments so far.
The crisis centres around three main characters: President Maithripala Sirisena, ousted prime minister Ranil Wickremesinghe, and former strongman president Mahinda Rajapaksa.
The three were pitted against each other in a different combination during the last elections that saw Sirisena elected to power.
Sirisena and Wickremesinghe are ideological opponents who had formed a coalition to defeat Rajapaksa in the 2015 elections, and they have now reverted to being on opposing sides.
Rajapaksa, who was president from 2005 to 2015, is considered a hero by some in Sri Lanka's ethnic Sinhalese majority because he oversaw the end of a 25-year civil war by crushing ethnic minority Tamil rebels in 2009. By others, he is considered a strongman who is close to China. His time in power had been marred by allegations of war-time atrocities, corruption and nepotism.