While Jaitley's seat from Uttar Pradesh is going to be retained by the BJP, given its majority in the state Assembly, the party and its ally Janata Dal (United) are eyeing Jethamalani's seat from Bihar, from where the late member represented RJD in the Upper House of Parliament.
In the 245-member Rajya Sabha, the BJP has 80 members and along with its allies, its strength is 114, 9 short of the majority mark.
The ruling alliance has so far been helped by parties like TRS and YSRCP, which are not part of the coalition, in passing legislations in the Upper House. However, the NDA needs majority on its own in the House to make things easier for it.
The BJP has not yet decided on candidates for the by-elections.
In Uttar Pradesh, the Opposition is not keen to put up any candidate as the numbers are clearly in favour of the ruling party, said a leader from the Opposition camp.
The state recently sent three members to the Rajya Sabha Neeraj Shekhar, Surendra Nagar and Sanjay Seth - who were Samajwadi Party MPs before they quit to join the BJP. All the three were elected uncontested.
Regarding Jethmalani's seat, there is no clarity as to whether the NDA candidate would be from BJP or JD(U). Sources say that the candidate might be from the BJP.
JD(U) leader and Chief Minister Nitish Kumar is a tough bargainer and will negotiate hard on the seat, a party source said.
In the state Assembly, the combined strength of NDA is 125 while UPA has 102 MLAs. Therefore, the Opposition is in no contention if the NDA fields a common candidate from there.
Sources say a decision on fielding of candidate for the Rajya Sabha polls by the NDA could be linked to a possible reshuffle and expansion of cabinet by Kumar after Dussehra.
The two parties are currently holding discussions in this regard, the sources said.
BJP is said to be already upset with a recent decision by Kumar to rename Bailey Road as Nehru Path.
A Congress MLA said any contest is healthy in a democracy but the UPA candidate is unlikely to win. However, its ally RJD is likely to field a candidate.
( With inputs from IANS )