Though a decision on the candidate will take some time, the process of evolving a consensus is gaining momentum.
Congress President Sonia Gandhi has initiated the process of bringing opposition parties together for the election slated in July in a bid to evolve a consensus on a candidate.
This also being seen as a precursor to the possibility of opposition parties coming together to take on the BJP-led National Democratic Alliance in the 2019 Lok Sabha polls.
Gopalkrishna Gandhi, grandson of Mahatma Gandhi, who was Secretary to the President when R Venkataraman held the post, is also said to have a good equation with West Bengal Chief Minister Mamata Banerjee, when he was Governor there. He himself has acknowledged that he has been approached.
Sonia Gandhi has over the past few days met Nationalist Congress Party leader Sharad Pawar, National Conference's Working President Omar Abdullah, Janata Dal-United leader and Bihar Chief Minister Nitish Kumar and Communist Party of India-Marxist chief Sitaram Yechury, CPI leader D Raja, and spoken to Samajwadi Party leader Mulayam Singh Yadav and Rashtriya Janata Dal chief Lalu Prasad.
Mrs Gandhi, who was admitted to the Sir Ganga Ram hospital due to food poisoning on May 9, is believed to have spoken to Trinamool Congress chief Mamata Banerjee from the hospital. The two are likely to meet on May 16. She will also meet DMK leader MK Stalin and Bahujan Samaj Party chief and former Uttar Pradesh Chief Minister Mayawati in the coming days.
"Sonia Gandhiji is trying to build a consensus on the presidential election over phone, and even by meeting leaders of the opposition parties. But we are waiting for the BJP to announce their candidate. Let them first declare their candidate," JD-U leader KC Tyagi told IANS.
Asked if consensus has been arrived at on any candidate, Mr Tyagi said: "A consensus has not been yet reached on any of the names. Let the notification be issued. But we have done our homework already. We will all contest the elections together."
Asked about the names of probable candidates doing the rounds, Mr Tyagi said: "Gopalkrishna Gandhi is a good name, but no consensus has been reached on that. Meira Kumar is also a good name, Sharad Yadav is also a good name."
"No consultations have taken place formally on the names together. Till the BJP announces its candidate or till the election date is announced, all this is just preliminary talk," he added.
A senior Left leader told IANS that the united opposition will wait for the BJP to announce their candidate. He also said that they will announce the name in the end.
"Announcing the name may land the candidate in a legal entanglement, like BJP patriarch LK Advani. Immediately after his name started doing the rounds for presidential candidature, the Supreme court revived the conspiracy charge against him on the Babri Masjid demolition," said the leader.
Janata Dal-Secular leader Danish Ali said they will first wait for the government to announce its candidate and only then will they take a stand on it.
"If the government proposes a consensus candidate it will be good for democracy. The government should consult the opposition parties before taking any decision.
"If we don't agree with the government's proposal and if the candidate is not suitable for Rashtrapati Bhavan, if he comes from the right-wing ideology, then the opposition will be forced to field a candidate in that scenario.. And JD-S will stand by the opposition parties," Danish Ali told IANS.
AIADMK leader V Maitreyan told IANS: "We'll have to see who are the candidates first (from both sides) and also how the Tamil Nadu scenario unfolds. It's too early to comment on this."
However, Odisha Chief Minister Naveen Patnaik-led Biju Janata Dal and Shiv Sena, which have been non-committal on the issue so far, will play a crucial role in the presidential elections.
Sources in the BJD said that if Jharkhand Governor Draupadi Murmu's name is proposed by the ruling establishment, the party may have difficulty in opposing her. Draupadi Murmu's name has been doing the rounds for the top post. She is a tribal politician, who hails from Odisha.
Opposition parties are also trying to garner support from the Shiv Sena and some of its leaders are in talks with Shiv Sena leaders.
A Congress leader said that if Sharad Pawar becomes the opposition candidate, the Shiv Sena may extend support to him.
In another unity move, DMK leader Kanimozhi met Sonia Gandhi last week and invited her for her father and DMK chief M Karunanidhi's 94th birthday celebrations in Chennai.
Mr Karunanidhi's birthday on June 3 is likely to be attended by leaders from several opposition parties, including Nitish Kumar, Lalu Prasad, Sitaram Yechury, D. Raja, National Conference leader Farooq Abdullah and Sharad Pawar. Kerala Chief Minister and CPI-M leader Pinarayi Vijayan may also attend.
The term of President Pranab Mukherjee ends in July. The BJP-led NDA appears to have an advantage as it has a comfortable majority in the Lok Sabha and rules many of the bigger states.
The electoral college for the election of President consists of elected members the two Houses of Parliament and members of the legislative assemblies and councils.