Addressing a press conference last Friday, Singh had said it would be "disastrous" for the country to have the BJP stalwart as the Prime Minister. Modi is BJP's Prime Ministerial candidate for this year's general elections.
The party adopted a political resolution on the opening day of its two-day State Executive meeting, strongly condemning Singh for his anti-Modi remarks.
It also criticised Congress President Sonia Gandhi for terming the Gujarat Chief Minister as "Maut Ka Saudagar" (merchant of death) in 2007.
It called upon the party activists to ensure BJP's victory in the coming Lok Sabha polls and work in the same spirit as they did in Madhya Pradesh, where the saffron outfit retained power after an improved performance in the just- concluded Assembly election.
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"The BJP workers will ensure that the mission of making Modi India's Prime Minister succeeds," Sharma later told reporters.
To a question, he said the BJP does not consider Aam Aadmi Party (AAP) or any other political outfit posing a challenge to it.