Here are the Top 10 developments in this big story:
After a meeting with the Governor on Sunday, state BJP chief Chandrakant Patil told reporters: "The mandate of the people was for the Shiv Sena-BJP combine. We cannot form the government on our own".
The BJP announcement came on Sunday evening after two rounds of meeting of the party's core committee a day before it was expected to form government. Last week, Chief Minister Devendra Fadnavis had met party chief Amit Shah and Mohan Bhagwat, chief of the BJP's ideological mentor, the Rashtriya Swayamsevak Sangh.
Asked to respond to the BJP announcement, Sanjay Raut had told reporters, "Maharashtra will have Sena's chief minister at any cost. Uddhav Thackeray on Sunday informed the party MLAs that Sena will have its chief minister".
Neither Sena, nor the BJP has the numbers to form government on their own. The Congress and the NCP, too, lack the numbers and both parties earlier said that they were ready to sit in the opposition.
In an editorial in Saamana, the party mouthpiece, the Sena last week said: "With 54 MLAs of NCP, 44 Cong MLAs and few independents, we can reach majority. The Sena can present its own Chief Minister and for that, 3 parties with independent ideology should form policies which are acceptable to all".
But after a meeting with Sharad Pawar, Congress chief Sonia Gandhi had ruled out the possibility of aligning with the Shiv Sena.
The Sena has been unflinching in their demand for half the cabinet berths and a rotational system for the Chief Minister's post, claiming it was an agreement made with BJP chief Amit Shah ahead of Lok Sabha polls. The party got furious after the BJP disagreed and denied that such a deal was made.
On Saturday, as the term of the legislative assembly ended amid a raging feud between the allies, Governor Bhagat Singh Koshyari had invited the BJP to form government.
After the Governor's invite, the Sena moved its legislators to a resort in Madh, two hours away from Mumbai. "We believe that the BJP will try all means to horsetrade MLAs," said Sanjay Raut.
The Sena won 56 seats in the 288-member Maharashtra assembly and claim to have the support of 65 MLAs. The BJP won 105 seats. The Congress has 44 MLAs and its ally, Sharad Pawar's NCP, 54.