Thousands of Sinhala voters took part in the Joint Opposition rally in Colombo, led by the former Sri Lankan president, Mahinda Rajapaksa.
Rajapaksa, accompanied by his brother, Gotabaya and son, Namal waved at the crowds and pledged to continue the rally until dawn.
Supporters had travelled to the rally from across the South of the island, along with several Buddhist monks.
The rally comes as Rajapaksa publicly announced that he was in the process of finding out whether he would be able to contest for the presidency once again.