Rajapakse, who is also the finance minister, had raised salaries, reduced taxes and slashed utility tariffs before announcing on Thursday that he will seek an unprecedented third term as president a move only made possible after he pushed through constitutional changes.
He called the election two years ahead of schedule in an apparent bid to seek a fresh mandate before his party’s popularity tumbles further after dropping over 21 percent in September local elections.
While Rajapakse remains generally popular with majority Sinhalese voters after he oversaw the end of a 37 year war against Tamil separatists in 2009, critics say he has become increasingly authoritarian.
A key coalition partner, the JHU, or party of Buddhist monks, walked out of the government on Tuesday, accusing Rajapakse of failing to deliver promised democratic reforms.
Rajapakse had believed the United National Party would field a candidate, but Sirisena’s entry took him by surprise as did the unity displayed by the one time fractured opposition party.
The contest is taking place against a backdrop of growing international pressure over the Rajapakse administration’s human rights record.
Rajapakse is struggling to avoid international censure over claims his troops killed 40,000 Tamil civilians in the bloody finale of the fighting, an issue that has overshadowed his ongoing chairmanship of the Commonwealth.