"I thank the UNP (United National Party) for choosing me as the common opposition candidate," Maithripala Sirisena, the No 2 in the Rajapaksa government, told a packed press conference, a day after the president announced his intention to seek a third term.
Sirisena, 63, was flanked by former president Chandrika Kumaratunga and several other parliamentarians who have defected to opposition ranks. Fisheries Minister Rajitha Senaratne has also defected to opposition ranks.
"One family took control of the entire government", he charged. "The country is heading towards a dictatorship."
"The entire economy and every aspect of society is controlled by one family," he said referring to Rajapaksa's brothers who include the speaker of parliament Chamal Rajapaksa.
More From This Section
"Corruption is rampant, there is no rule of law," he said.
Sirisena's defection is the biggest political setback for Rajapaksa, who enjoys popularity among Sinhalese majority for leading the Sri Lankan forces to victory after a nearly three-decade war against the Tamil rebels.
Sirisen, a senior Sri Lanka Freedom Party (SLFP) member, said he has suffered under Rajapksa's rule.
He said his partymen were isolated in the United People's Freedom Alliance coalition leading the government. "So there is a need to reorganise the party."
"We have resolved to abolish the executive presidency within 100 days. I will appeal to the voting public to elect me as the president to do this".
Sirisena said he will create fully independent public, judicial and election systems, if elected.
"We will reestablish true media freedom in the country. We shall fully reform the election system to ensure free and fair elections," he said.