Arvind Kejriwal alleges that the BJP is setting up an "artificial battle" in Delhi.
A poster saying "Delhi Speaks - Modi for PM, Arvind for CM" made a brief but much talked about appearance on the website of Arvind Kejriwal's Aam Aadmi Party on Friday. The party claims it was "mischief" by an outsider.
"It looks like some mischief; someone intruded our website, we are investigating the matter," said AAP leader Ashutosh.
The poster, with images of Mr Kejriwal and Prime Minister Narendra Modi, vanished from the site as AAP faced adverse comments on social media from critics. Some called the party "desperate" for using PM Modi in their campaign.
Hours before the phrase appeared on AAP's website, Mr Kejriwal told NDTV, "People I meet in Delhi are saying Modi for PM, Kejriwal for Chief Minister."
The battle, he added, "is between (BJP's) Jagdish Mukhi and Kejriwal, not Modi and Kejriwal."
The two leaders were last pitted against each other during the April-May national election at Varanasi in Uttar Pradesh, where Mr Modi defeated the AAP chief with a massive margin of 3.7 lakh votes.
The BJP has announced that it will not project a chief ministerial candidate in Delhi, a strategy that has paid off in Maharashtra and Haryana, where the party fashioned its campaigns around what it perceives as the "Modi magic". Some in the BJP believe the party should not risk pitching a "weak chief ministerial face" against Mr Kejriwal, the man who last governed Delhi after a spectacular election debut a year ago.
Mr Kejriwal alleges that the BJP is setting up an "artificial battle" to make the Delhi polls seem like a face-off between him and PM Modi. "They are trying to do fraud on the people of Delhi....Modi will not run the city, it will be handed over to somebody else," he told NDTV on Thursday.