The election for the post of Vice President has seen UPA and its allies, the Left as also other parties supporting it from outside backing the incumbent.
A total of 788 Lok Sabha and Rajya Sabha MPs are eligible to vote in the poll to elect the 14th Vice President.
UPA managers are confident that Mr Ansari, 75, is set to get at least 500 votes in a contest in which he has a definite edge as far as the arithmetic is concerned.
The Congress itself has 204 members in Lok Sabha and 71 in Rajya Sabha. UPA constituents Trinamool Congress has 19 MPs in Lok Sabha and nine in Rajya Sabha; the DMK has 18 members in Lok Sabha and seven in Rajya Sabha, the NCP nine in Lok Sabha and seven in Rajya Sabha and the RLD has five in Lok Sabha. The National Conference has three in Lok Sabha and two in Rajya Sabha.
Besides, the Samajwadi Party with its 22 members in Lok Sabha and nine in Rajya Sabha and the BSP with its 21 in Lok Sabha and 15 in Rajya Sabha are backing Mr Ansari, who is also being backed by the entire Left block with 38 members in both Houses of Parliament.
Unlike the Presidential poll held last month, which had split the NDA with the JD(U) and the Shiv Sena breaking ranks to vote for UPA candidate Pranab Mukherjee, Jaswant Singh has the backing of a united NDA for his Vice Presidential bid.
The BJP has 114 members in Lok Sabha and 49 in Rajya Sabha; the JD(U) 20 and nine; the Shiv Sena 11 and four; and the Shiromani Akali Dal four and three, respectively.
While the AIADMK, which has 14 MPs in Parliament, yesterday announced its support to Mr Singh's candidature, the BJD with 18 members in Lok Sabha and seven in the Rajya Sabha has decided to abstain from voting.
Ahead of the poll, UPA Chaiperson Sonia Gandhi yesterday hosted a lunch for UPA constituents and the parties supporting it from outside, which projected a complete picture of unity.
The Trinamool Congress MPs attended Mrs Gandhi's lunch and the party is expected to go public with its support Ansari ahead of the polls.
Not only all UPA constituents but also the chiefs of the Samajwadi Party and the BSP, Mualyam Singh Yadav and Mayawati, attended the lunch.
The two leaders, arch rival in Uttar Pradesh politics, had not attended any such programme together for several years.
At the All India Congress Committee (AICC) headquarters, party general secretary Digvijaya Singh held interactions with several MPs, especially those from Uttar Pradesh, to ensure voting is done properly during the Vice Presidential poll and no vote goes waste. The polling will take place from 10 am to 5 pm.
A total of 42 papers were filed by 31 candidates during the 14-day nomination process, of which four sets of papers submitted by Mr Ansari and three sets submitted by Mr Singh were accepted. The nomination papers of 29 others were rejected on various grounds.
Though the numbers are stacked highly against Mr Singh, the BJP is making all efforts to put up a respectable fight.
In Chennai, Tamil Nadu Chief Minister Jayalalithaa yesterday extended the AIADMK's support to the NDA nominee Jaswant Singh, saying she firmly believes that there has to be an opposition in a true democracy.