AAP does worry us, says BJP

"If the AAP candidates manage to make a dent, get even a few thousand votes, there can be serious trouble ahead for the BJP," he added.

For instance, BJP's outgoing MP from Agra city, Ram Shankar Katheria, won by just 9,000 votes in 2009.

"This is not a decisive margin," Jain said. "The AAP can easily manage to get 15-20,000 votes and create problems for the BJP."

In Mainpuri, the AAP candidate, Hardev Singh, has a formidable reputation as an upright former government officer.

He may not win against Samajwadi Party chief Mulayam Singh Yadav but can definitely queer the pitch for BJP candidates in and around Mainpuri, political observers say.