Singh, who was in Delhi on Wednesday, said over phone: "The party is already on a strong footing in the state. The confidence of the workers is at an all time high. We will definitely win the upcoming bypolls.
"People are happy with the welfare work done by the Narendra Modi government at the Centre and the Yogi Adityanath government in the state," he said.
Singh said the Bharatiya Janata Party (BJP) would also win the Zila Panchayat polls, scheduled to be held next year.
Asked about his priorities, the BJP leader said: "At the moment, the focus of the party is on the membership drive. The target is to bring more people into the BJP fold and we are giving momentum to the organisational activities."
He said the new assignment was a task given to him and as a party worker he would fulfil this responsibility with sincerity.
The by-election to 12 assembly seats was necessitated as the sitting MLAs were elected to the Lok Sabha, while the vacancy in Hamirpur was caused due to the disqualification of Bharatiya Janata Party (BJP) legislator Ashok Kumar Singh Chandel who was convicted in a murder case.
The constituencies that fell vacant following the election of the sitting MLAs as MPs are Manikpur, Iglas (SC), Zaidpur (SC), Gangoh, Balha (SC), Rampur, Jalalpur, Pratapgarh, Lucknow Cantonment, Govind Nagar and Tundla (SC). Hamirpur fell vacant after Chandel was disqualified.
The by-elections are likely to be held after the monsoon.
( With inputs from IANS )