After facing criticism that it favours only Yadavs while in power, the Samajwadi Party (SP) is now attempting social engineering in Uttar Pradesh through a rainbow coalition of smaller backward and Dalit castes, to challenge the BJP in the 2019 Lok Sabha elections.The support of the Bahujan Samaj Party proved decisive for the SP in winning the Gorakhpur and Phulpur seats in the recent Lok Sabha byelections.The two parties are yet to reach a full-fledged alliance, but the byelection win was the first victory for Mr. Akhilesh’s experiment in social engineering.A gambleIn Gorakhpur, the SP gambled on an outsider — Pravin Nishad, 29, son of Nishad Party president Sanjay Nishad, who commands a considerable presence among the riverine Mallah caste (OBC) and its various sub-castes such as Nishad and Kewats in eastern U.P. The alliance in Gorakhpur was not a one-off though. The Nishad Party had, in December 2017, extended full support to the SP in the Sikandra Assembly byelection in Kanpur. The SP lost the seat but made huge gains in vote share. In the 2017 Assembly election, the Nishad Party managed to secure over 5.4 lakh votes in the 72 seats it contested, mostly in Purvanchal, and is capable of turning the results in favour of the SP.Another major caste the SP has been wooing is the Pasi community, the second largest Dalit caste in U.P. After roping in former BSP general secretary and Pasi face of the BSP Inderjeet Saroj last September, the SP soon inducted another prominent caste leader and BSP founder, R.K. Chaudhary, and former Minister Shyamlal Rawat. Their entry strengthens the SP in the Allahabad-Lucknow region.Mr. Akhilesh has confirmed the support of the Janwadi Party (Socialist) Party, which commands a presence among the Noniya Chauhan caste in eastern Uttar Pradesh. Another important OBC caste bloc on the SP’s radar is the Maurya (Kushwaha-Sakhya-Saini) community. Naval Kishore, son-in-law of Swami Prasad Maurya, State Minister and former OBC face of the BSP, joined the SP on Saturday.