Addressing an election rally in the south western region of Ratnapura yesterday, Sirisena urged the SLPP supporters to rejoin his Sri Lanka Freedom Party (SLFP).
"Please leave that garbage party and join hands with me. If all 96 MPs elected to parliament under SLFP come to my house tomorrow morning, I will form the government," he said.
His comments came in the midst of his current stand-off with his unity government partner Prime Minister Wickremesinghe's United National Party (UNP).
"There are no permanent friends or enemies in politics," Sirisena said, extending the olive branch to Rajapaksa's loyalists.
More From This Section
Rajapaksa's new party is expected to create dents in the SLFP support at the local election.
Sirisena was backed by the UNP in the presidential election of 2015 against Rajapaksa. This resulted him from being sacked from the SLFP by Rajapaksa.
Sirisena in the recent weeks has taken the UNP to task while campaigning for the February 10 local council election.
Analysts, however, say Sirisena lacks numbers in the 225- member parliament to sack Wickremesinghe and appoint a new prime minister of his choice. The sitting premier cannot be removed other than through a motion of no confidence.