Sources in BJP said the party, with around 30 surplus votes, could ensure victory for 54-year-old Mallya who is contesting as an independent with the support of 27 member JD-S group and an Independent MLA Varthur Prakash.
Mallya, who was elected to the Rajya Sabha as an Independent for the first time in 2002, needs 45 first preference votes for victory.
BJP has convened its legislature party meet tomorrow to discuss its strategy for the Rajya Sabha polls.
The party has fielded its senior leader M Venkaiah Naidu, for the third successive term and state unit spokesman Ayanur Manjunath, who had sacrificed his claim for Shimoga Lok Sabha seat last year in favour of Chief Minister B S Yeddyurappa's son B Y Raghavendra.
The sources said the BJP would issue a whip to its MLAs.
Congress which is staking claim for the second seat has fielded senior leader T V Maruthi, besides former union minister Oscar Fernandes.
KPCC President R V Deshpande told reporters that the party's strategy for Rajya Sabha election would be firmed up at its legislature party meeting tomorrow.
Y S V Datta, JD-S spokesman said, "We will not issue whip. But our MLAs will go in a group and cast their votes."
Against the backdrop of Mallya getting BJP support, Congress has to be content with the victory of Oscar Fernandes and does not appear to be in a position to drum up support for Maruthi. The ruling BJP, however, is in a position to ensure facile victory of Naidu and Manjunath.
In the 224-member Assembly, BJP has 116 members, Congress 74, JD-S 27 and Independents six. One seat is vacant.