UP polls: Swami Prasad Maurya is a powerful OBC (Other Backward Class) leader.
Swami Prasad Maurya, who seems to be leading an exodus from the BJP just weeks before the Uttar Pradesh election, had been exploring change with rival Akhilesh Yadav for some time, sources say.
Swami Prasad Maurya reportedly got a hint from the BJP that his supporters may not be the party's candidates for the February-March polls.
Mr Maurya, a powerful OBC (Other Backward Class) leader, has taken along a loyal group of leaders in his political travels from Mayawati's Bahujan Samaj Party (BSP) to the BJP in 2016 and to the Samajwadi Party now.
That group - including the four MLAs who quit with him today - were unlikely to be fielded by the BJP this time, sources say.
Without his entourage, Swami Prasad Maurya would have been reduced to any other MLA under Prime Minister Narendra Modi and Yogi Adityanath.
With that in mind, say sources, Mr Maurya opened talks with Akhilesh Yadav - the man he was meant to help the party defeat in polls.
Mr Maurya decided to make his move the moment he realised that he had not much more to extract from the BJP.
That happened to be on a day UP Chief Minister Yogi Adityanath arrived in Delhi for strategy talks with the BJP leadership.
Sources say the BJP leadership should have seen this coming.
The countdown possibly started two months ago, when Mr Maurya met with Union Home Minister Amit Shah to complain about Yogi Adityanath.
This was a pattern over the past two years - MLAs complaining about Yogi Adityanath's style of functioning and perceived arrogance.
Mr Maurya and MLAs close to him were hopeful that Yogi Adityanath would be reined in by PM Modi, but that never happened.
Today, the BJP leadership reportedly urged UP Deputy Chief Minister Keshav Prasad Maurya to make a belated effort to reach out to Swami Prasad Maurya and the other defectors. Mr Maurya's response was a snub.
The exits will likely cost the BJP in the UP election, where caste is a big factor.
Swami Prasad Maurya is believed to have 15 to 20 MLAs on his side. The Maurya community make up about five per cent of UP's population and Swami Prasad Maurya is one of its strongest faces.
The exit of a popular backward caste leader will spur a last-minute change of poll strategy for the BJP. Mr Maurya is among the many leaders who propelled the BJP to power in 2017 with social and caste engineering.
The BJP's loss is Akhilesh Yadav's gain.
With Mr Maurya on board, the Samajwadi Party hopes to get the "social and caste engineering" right in these polls.