With the Left parties deferring its decision on the presidential election, Congress president Sonia Gandhi met senior party leaders on Tuesday evening to finetune the election strategy including finalising the United Progressive Alliance nominee.

Sonia held consultations with Pranab Mukherjee, A K Antony and Ahmed Patel as the Left parties, after a joint meeting, announced they would take a decision after parleys with Dravida Munnetra Kazhagam supremo and Tamil Nadu Chief Minister M Karunanidhi on Wednesday.

Karunanidhi's party is the third largest constituent of the ruling UPA while the Left parties give the coalition crucial outside support with some 60 Lok Sabha members.

Karunanidhi will arrive in Delhi on a three-day visit during which he would discuss the presidential issue with Prime Minister Manmohan Singh [Images] and Sonia.

Sonia's discussions with her senior colleagues came hours after Bahujan Samaj Party supremo Mayawati announced her party's support to the UPA nominee, giving a major boost to the ruling alliance.

BSP holds substantial number of votes to tilt the scales in the presidential election.

The three Congress leaders were entrusted with the task of talking to allies in order to evolve a consensus.