A defamation notice is being served on the PCC chief for levelling an unfounded allegation against the BJP without producing any evidence, state BJP president Ajay Bhatt said in a statement here.
Upadhyay had accused the BJP of spending Rs 700 crore to "buy" Congress MLAs and dislodge the Harish Rawat government.
Bhatt urged the CBI to probe all the sting operations carried out against Rawat.
Praising Governor K K Paul for taking some "very good decisions" in public interest during President's Rule, the BJP leader said the party will protest any attempt by Rawat government to reverse policydecisions taken during central rule.
"Policy decisions taken during President's Rule should not be changed. If there is an attempt by Rawat government to reverse them, the party will protest it," Bhatt said.