Former Sri Lankan president Chandrika Kumaratunga has pledged her support for the main opposition candidate in a presidential election on Tuesday.
Ms Kumaratunga says she's deeply concerned about violence during the campaign and is urging her supporters to vote for the former army General Sarath Fonseka.
Four people have died and hundreds have been wounded in election clashes.
Mrs Kumaratunga is a senior member of Mr Rajapaksa's Sri Lanka Freedom Party.
She said she was deeply concerned about violence, intimidation and corruption in the poll.
In an increasingly bitter campaign, the opposition has accused the ruling party of planning a coup to hang on to power.
The ruling party said the accusations were "baseless" and an attempt to cover for an inevitable defeat.
Mrs Kumaratunga is the daughter of the founder of the Sri Lanka Freedom Party and the dynasty still has big support in the country.
Mrs Kumaratunga herself served as president from 1994 to 2005.
The BBC reports President Rajapaksa and General Fonseka are closely associated with the defeat of the Tamil Tigers last May, but they fell out bitterly soon after.
Saturday was the final day of campaigning.