The ex-deputy CM of Punjab was campaigning for Sirsa.
"Basically, it is a referendum on the Kejriwal government. It will reflect the feelings of the people of Delhi who are deeply distressed by over two years of AAP rule," he said.
Badal said "more than 37" AAP candidates "lost" their security deposits in recently concluded elections in Punjab and the party will face the "same fate" in the April 9 bypoll.
Union minister Venkaiah Naidu and Delhi BJP president Manoj Tiwari had campaigned for Sirsa yesterday. Bollywood actor and BJP MP Paresh Rawal also campaigned for him.
Sirsa is pitted against Congress candidate Meenakshi Chandela and AAP's Harjeet Singh in a three-cornered contest.
The seat fell vacant early this year after AAP's Jarnail Singh quit as MLA to contest Punjab Assembly poll against SAD patron Parkash Singh Badal which he lost.