BJP MLA from Mumbai's Kandivali East Atul Bhatkhalkar, in his letter, asked Thackeray to show courage to shut down state-funded madrasas and prove his "Hindutva credentials".
He also claimed that those legislators who went to BJP before 2019 Assembly polls are eager to return back to his party.
On Monday, BJP's Rajya Sabha member Narayan Rane met Maharashtra Governor B S Koshyari and demanded imposition of President's rule
Malik, however, said that such a problem has not arisen with other states like Bihar, Rajasthan, and another BJP-ruled state, Madhya Pradesh.
Earlier on Wednesday, Amit Shah said that there was 'a deep conspiracy' behind the Delhi riots and no one will be spared who is guilty of violence irrespective of his religion, caste or party.
Maharashtra cabinet minister Nawab Malik said that the Muslims' development will also reflect in the country's overall development.
Leader of Opposition in the Assembly Devendra Fadnavis also claimed that a quota for Muslims would be unconstitutional and affect OBC and Maratha reservations.
This comes after an application was filed before the Bhima-Koregaon judicial inquiry commission requesting it to summon NCP chief Sharad Pawar in the matter.
The NCP also alleged that the Centre's move is aimed at covering up the wrongdoings of the previous BJP-led government in Maharashtra.
The NCP leader's comments came after protests against the amended citizenship law turned violent in various districts of the state, in which a number of people died and scores sustained injuries.
The Shiv Sena also hit out at the BJP saying that the poll poll trends show that 'people are not buying the Amit Shah-led party's politics'.
Clearing its stand on the CAB in the parliament, the Shiv Sena on Monday had said if the intention of the bill was to 'create a vote bank' then it is not good for the country.
The Citizenship (Amendment) Bill (CAB)seeks to grant Indian citizenship to non-Muslim refugees from Pakistan, Bangladesh and Afghanistan escaping religious persecution there.
The triple talaq bill was introduced in the Lok Sabha to gain political mileage and not for the interest of Muslim community, the Sharad Pawar-led NCP said today.