His comments came after Lankan Speaker Karu Jayasuriya earlier in the day slammed Sirisena's "unconstitutional and undemocratic" actions to sack Prime Minister Ranil Wickremesinghe and suspend Parliament, saying he will not recognise Rajapaksa as the new premier unless he wins a floor test.
"We have already got our 113 MPs, I will not take back the step I have taken forward... have taken all steps in accordance with the constitution," Sirisena told a public rally, referring to his decision to sack Wickremesinghe.
Sirisena suspended parliamentary proceedings until November 16 after abruptly firing Wickremesinghe and replacing him with Rajapaksa, a controversial former president, on October 26.
The Speaker had expected parliament to reconvene on November 7. However, Sirisena Sunday issued notice to reconvene Parliament on November 14.
Wickremesinghe, whose party dubbed the move a "constitutional coup", refused to vacate his official residence, saying he is the lawful prime minister and that the president has no constitutional right to replace him.
The rally, attended by thousands of supporters, was the first public show of Sirisena and Rajapaksa together after the island nation plunged into a constitutional crisis.
With eight United National Party and one Tamil National Alliance legislators defecting to Rajapaksa camp, he is now just eight seats short of the 'magic number' 113 to prove his majority in the 225-member House.
While addressing the rally, Sirisena said before opting for Rajapaksa as his prime ministerial choice, he had offered the premiership position to Speaker Jayasuriya and deputy PM Sajith Premadasa. "However, both of them refused to challenge their leader," Sirisena said.
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