NEW DELHI, March 23 -- Uttar Pradesh (UP) and Bihar will play critical roles in determining who forms the next government in Delhi. With 120 seats between them, out of which the Bharatiya Janata Party (BJP) won 93 seats last time (71 in UP and 22 in Bihar), this is the belt which made all the difference between BJP being the single largest force and attaining a majority on its own in 2014. This time around, it faces its most formidable challenge here in the form of a united Samajwadi Party(SP)-Bahujan Samaj Party(BSP) in UP, and a possible grand alliance led by the Rashtriya Janata Dal (RJD) in Bihar....