New Delhi, June 19: The Opposition parties have begun to recalibrate their strategy and shortlist names for a candidate for President as a contest looks increasingly possible now.

Nitish Kumar and Mayawati are nursing reservations about challenging Ramnath Kovind, the NDA candidate, but the principal Opposition parties are hoping to turn them around by coming up with a Dalit nominee to counter the Bihar governor.

The final decision is not expected before a June 22 meeting. But three names were being doing the rounds among multiple Opposition parties tonight: Prakash Ambedkar, the grandson of Babasaheb Ambedkar; Sushil Kumar Shinde, the Congress veteran and former home minister; and Meira Kumar, the former Lok Sabha Speaker.

The possibility of fielding a tribal candidate is also being explored. If, by chance, the Opposition decides not to play the caste game and make it a purely ideological battle, efforts to field former Bengal governor Gopalkrishna Gandhi are likely to be reactivated.

Two key Opposition parties are said to be in favour of Shinde because he is from Maharashtra, where the Shiv Sena is yet to give a commitment to the BJP.

These two parties feel that every effort must be made to keep the Sena on the Opposition's side in the presidential election. Prakash too hails from Maharashtra, which strengthens his credentials as well.

Sources said Lalu Prasad, Nitish's Bihar ally, too was trying hard to dissuade the chief minister from supporting Kovind. The sources claimed that Lalu Prasad was prepared to put the alliance at stake if Nitish broke ranks and voted with the BJP.

K.C. Tyagi, a senior JDU leader, conceded that Kovind's candidature had put his party in an uncomfortable position while insisting the final decision would be taken after consultations. Asked if the party would attend Thursday's Opposition meeting to discuss its nominee, he said it would.

Lalu Prasad is unlikely to attend Thursday's meeting as he has a court hearing in Jharkhand the same day.

Opposition sources said that Nitish had initially been in two minds because of his "personal rapport" with Kovind and the governor's "caste", but was told by the Congress, RJD and the CPM that such factors should not count. The sources claimed that Nitish appeared to have been convinced.

Sonia Gandhi called Nitish, Lalu Prasad, Sharad Pawar, Mamata Banerjee, Mayawati and other leaders to sound them out.

The reservations the JDU and Mayawati harboured about opposing Kovind are rooted in his Dalit background. Mayawati has made it clear that she is positively inclined towards the current Bihar governor but "only if the Opposition does not announce a popular Dalit name".

While the Congress has for sometime suggested Meira Kumar's name, the difficulties some parties may have in supporting a long-time Congress politician like her for the President's post has forced the Opposition to look elsewhere.

A name that came into play this afternoon after the announcement of Kovind's candidature was that of Prakash, Ambedkar's grandson.

Another possibility being considered is that of a tribal candidate since India has never had a President from among the Scheduled Tribes, though the country had its first Dalit President in 1997 with the elevation of then Vice-President K.R. Narayanan.

"Even then, there was a contest," CPM general secretary Sitaram Yechury pointed out to counter the BJP's contention that Kovind should be elected unopposed because he was a Dalit.

"Every presidential election, except the one in 1977 in which Neelam Sanjeeva Reddy became President, was contested," Yechury said, adding that his party got to know about Kovind's candidature from the media.

Barring the Congress, which was informed by the government of the choice, all other Opposition parties appear to have learnt about Kovind's selection from the media.

One overriding feeling among Opposition politicians today was that the government had not sincerely tried to evolve a consensus.

Derek O'Brien of the Trinamul Congress said: "The name was announced at the BJP press conference. That's how we got to know. Not even informed. How many of you logged onto Wikipedia today? I did."

The Opposition felt it must not succumb to the government's Dalit card but field a contestant since, sources said, Kovind's background didn't sit well with expectations of a "neutral" President who would protect the constitutional scheme.

"We hoped the government would try to evolve a consensus.... Now there is no scope for a consensus," the Congress's Ghulam Nabi Azad said.

Mamata was on her way to The Netherlands to attend a UN programme when Kovind's name was announced. Phone calls were streaming in when the chief minister landed in Dubai. Mamata told reporters: "I have never heard his name. He may be a governor. I know so many governors. But never heard of him.... Jani na... chini na," she said.

She added that Andhra Pradesh chief minister Chandrababu Naidu too had "expressed his surprise at the selection of the candidate". Naidu later supported Kovind's candidature.

Mamata underscored that she was "not for a moment saying Kovind is unfit to be President".

"To support someone, we must know the person. The candidate should be someone who will be beneficial for the country," she said.

"There are other big Dalit leaders in the country. Just because he was the leader of the Dalit Morcha of the BJP they have made him the candidate."

Mamata added: "The office of the President is a key post. Someone of the stature of (current President) Pranab Mukherjee, or even Sushma Swaraj or (L.K.) Advaniji, could have been made the candidate."