Prime Minister Narendra Modi's acronym for the opposition coalition in Uttar Pradesh - sarab - at his election rally in Meerut had a furious Congress demanding his apology and accusing him of stooping to a new low. "Sapa (Samajwadi Party) ka 'sa', RLD ka 'Raa' aur Baspa (BSP) ka 'ba', matlab 'sharab'. Take the 'Sa' of Samajwadi Party, 'Ra' or Rashtriya Lok Dal and 'Ba' of Bahujan Samaj Party)," PM Modi said to a large public gathering as he launched his campaign in Uttar Pradesh for next month's national election.