NEW DELHI: for a new deputy chairman of the Rajya Sabha (RS) will be held on Thursday. The post of the deputy chairman has been lying vacant since June following the retirement of PJ Kurien, who was elected to the Upper House of Parliament on a Congress ticket from Kerala. Here's all you need to know about who has been nominated, how the numbers will work in or against their favour and what the broader significance of this contest is ahead of the 2019 general elections:

* The BJP-led NDA's nominee is Harivansh Narayan Singh of the JD(U). He's a Parliamentarian from Bihar and a former journalist. In nominating a JD(U) candidate, the BJP is attempting to reach out to its allies who have been complaining about being left out.

* Who the opposition's candidate will be is still unclear. The NCP's Vandana Chavan was one name being floated in the hope that the Shiv Sena will back her because she's from Maharashtra. Another name being floated is that of Congress MP from Karnataka BK Hariprasad. On Wednesday morning, unnamed sources told news agency ANI that Hariprasad will be the Congress candidate.

* Following the failed no-confidence motion against the government in the Lok Sabha last month, the contest for the post of RS deputy chairman is the next big test of opposition unity.

* The BJP would, of course, find it advantageous to have its candidate win because then the chairman (Venkaiah Naidu) and his deputy would both be their choices.

* For the Congress, retaining the post would come as a big boost. In addition, if it gets support from other opposition parties, that would point to a building of opposition unity.

* But how do the numbers stack up? The current strength of the Rajya Sabha is 244, so the support of 123 members would be needed for a win. That is, if it's a full house, which may not be the case since the demise Tuesday night of DMK supremo M Karunanidhi in Chennai.

* The lack of majority in the Rajya Sabha has been a big problem for the BJP. The BJP-led NDA has 93 MPs, including those from the Shiv Sena with whom it isn't exactly chummy these days. As well, it's being said the Shiromani Akali Dal (SAD) is displeased with the BJP's choice of a JD(U) candidate over its own MP Naresh Gujral. BJP members are said to have reached out to SAD. Not supporting the NDA, it was pointed out, would only compromise the Akalis in their fight with their chief rival, the Congress party.

* The Congress is the largest party in the RS with 50 seats. The opposition, including the Congress, claims it has 114 votes on its side, including two from the YSR Congress. The Congress-led UPA plus regional parties' tally is 118.

* In what would not be good for the Congress, there is speculation that Mamata Banerjee's Trinamool Congress is not in favour of opposing the JD(U) candidate because it doesn't want to directly confront JD(U) chief Nitish Kumar's party.

* Meanwhile, there are at least 37 MPs who can tilt the balance. They are the AIADMK (13), BJD (9), TRS (6), PDP (2), INLD (1) and independents (6). In this situation, which party abstains and who actively supports which camp will be equally important.

* The BJD (with nine seats) is likely to support the ruling coalition's nominee, per news that emerged Tuesday evening. Nitish is said to have spoken with BJD chief Naveen Patnaik and this led to expectations the BJD will back the NDA even though there was no formal announcement.

* Without the BJD, the NDA's tally is a shade short of that of the UPA plus regional parties' 118. Some sources said the support of the AIADMK's 13 and the TRS's six MPs is all but in the bag for the NDA.

