The Congress not only retained hold over the NWCMC but also hugely improved its tally compared to 2012 when it had secured 41 seats, proving a major morale booster for the party reeling under a saffron onslaught.
He has claimed that the six corporators have been lured with promises; hence a thorough investigation should be carried out, Sawant said in his letter.
Shiv Sena spokesperson Neelam Gorhe hit back, saying the outcome was "a result of people's anger against the BJP's policies and a setback to Fadnavis".
In the 227-member BMC, the current party-wise position now is: Shiv Sena 91 and three independents, BJP 83 and two independents, Congress 30, Nationalist Congress Party nine, MNS one, Samajwadi Party six and All India Majlis-e-Ittehadul Muslimeen (AIMIM) two corporators. The Sena further has the support of four independents and the BJP has the support of two independents.
According to BMC officials, BJP candidate Jagruti Patel polled 11,129 votes in ward no. 116, while the Sena nominee, Minakshi Patil, got 6,337 votes. The constituency is, after all, one that Ashok Chavan's father late Shankarrao Chavan nurtured.
Despite being part of the National Democratic Alliance and partners in the ruling BJP-led Maharashtra government, relations between the Shiv Sena and the BJP have been increasingly choppy.
The party's fortunes, which were on the upswing after it came to power in the Nashik Municipal Corporation in 2012, declined in the next polls, with many of its corporators in the north Maharashtra city quitting ahead of the polls.
A senior Sena legislator, who did not wish to be named, said a stronger Congress in Maharashtra would be indirectly helpful for the Shiv Sena. "Ultimately, it is the BJP's effort to marginalise the Shiv Sena that is going to cause the BJP's downfall".
Sena leader Anil Parab said he has written a letter to the Konkan division commissioner, informing him about the induction of six MNS corporators in the party. "The situation in the state is no different".