NCP chief spokesperson Nawab Malik said it implied the BJP will resort to poaching.
Earlier, Fadnavis met Koshyari and tendered his resignation. Later, addressing the press conference, Fadnavis said the BJP will retain power in the state.
"While informing about his resignation during a press conference, Devendra Fadnavis claimed only BJP will form government. Why did not he make such a claim before the Honourable Governor then? What it is if not poaching?" Malik tweeted with a hashtag "MaharashtraPoliticalCrisis".
There has been no headway in government formation in the state even a fortnight after Assembly poll results were announced on October 24.
The BJP and Shiv Sena are locked in a tussle over the chief minister's post, resulting in a stalemate despite the poll results giving the saffron alliance a combined seat strength of 161, way past the 145 majority mark in the 288member House.