New Delhi: The ruling Bharatiya Janata Party (BJP)-led National Democratic Alliance (NDA) moved closer to clinching the post of deputy chairman of Rajya Sabha after key regional parties lined up behind their choice: Harivansh, a Janata Dal (United) member of Parliament (MP).

After a hectic night of negotiations, including interventions by Prime Minister Narendra Modi, BJP president Amit Shah and JD(U) chief Nitish Kumar, the arithmetic has swung back in the favour of the NDA.

Unless B.K. Hariprasad, the Congress MP and the choice of the opposition, pulls off an unlikely upset, Harivansh is likely to win the election scheduled for Thursday.

The momentum turned gradually in favour of NDA. PM Modi had set the ball rolling last Saturday when he met Telangana chief minister K. Chandrashekar Rao and head of the Telangana Rashtriya Samithi (TRS) on Saturday and sought the party’s support for the NDA candidate.

On Tuesday morning, Nitish Kumar all but sealed the verdict when he successfully appealed to the Odisha chief minister and Biju Janata Dal (BJD) head Naveen Patnaik to support the JD(U) candidate—a first time member of the Rajya Sabha. The BJD has nine members in the House.

“Harivansh is a very capable candidate for the crucial post. The choice is also significant because Janata Dal (United) or JD(U) does not have a representative in the Union cabinet, so in a way, the BJP is trying to accommodate JD(U) by supporting Harivansh for the top post," said a senior JD(U) leader, who is also a member of the Rajya Sabha.

Interestingly, the support of BJD, TRS and All India Anna Dravida Munnetra Kazhagam (AIADMK) is important for NDA as three parties together have 28 MPs in the Upper House.

“Nitish Kumar spoke to Odisha chief minister Naveen Patnaik on Tuesday morning and BJD has decided to support Harivansh. BJD has traditionally been opposed to Congress so we cannot support Congress. Harivansh is not a BJP candidate also, he is part of JD(U)," said a senior BJD parliamentarian.

While Modi and Kumar were busy getting support for the NDA candidate, BJP president Amit Shah had the responsibility of reaching out to NDA partners who were annoyed with the decision to nominate Harivansh as the contestant of the alliance.

Senior leaders of Shiromani Akali Dal (SAD) were annoyed with BJP because the party was keen that one of its leaders should be made NDA’s candidate. However, BJP decided to back JD(U) for the crucial polls.

“BJP president Amit Shah met Sukhbir Singh Badal on Tuesday evening. It was decided during the meeting that since BJP and SAD have been in an alliance for a long time, the election should sour the alliance," said a senior SAD leader in the know of development.

Meanwhile, Kumar also spoke to senior leaders of Shiv Sena, further improving the odds of a victory for Harivansh.

After being isolated by other opposition parties, Congress party zeroed down on Hariprasad’s candidature a night before nominations were filed on Wednesday.

At least three rounds of meetings took place on Tuesday with key opposition leaders and by the end of the second meeting in the evening, there was clarity that none of the non-Congress parties were willing to field a candidate for the post.

According to a senior Congress MP from Rajya Sabha, party president Rahul Gandhi is known to have reached out to Nationalist Congress Party (NCP) chief Sharad Pawar but it did not yield any result.

“The situation is very tight for us and I would say for now it is neck to neck. All the big opposition parties like NCP, DMK (Dravida Munnetra Kazhagam), SP (Samajwadi Party), BSP (Bahujan Samaj Party), RJD (Rashtriya Janata Dal), TMC (Trinamool Congress), and the Left parties are with us but lot will depend on who all decide to abstain tomorrow," another Congress leader from Rajya Sabha said requesting anonymity.

Earlier candidates from both NCP and DMK were being considered but top leadership from both the parties backed out by Tuesday evening, which several leaders claim is because the opposition did not have the numbers.

“As of now, our party has decided that they will abstain from voting. Congress has not reached out to the party for support so far. We will take a final decision ahead of the election," a senior Aam Aadmi Party leader said on condition of anonymity.

Anuja and Pretika Khanna contributed to this story.