SHILLONG: Starting its second phase of agitation against the National Institute of Open Schooling (NIOS), the Meghalaya SSA Schools’ Association (MSSASA) will hold a letter campaign at Khasi National Durbar Hall, Mawkhar on Friday. The MSSASA on Thursday said the letter campaign, which started on January 30, will end on February 4. The campaign in which 1235 teachers are taking part seeks the intervention of Prime Minister Narendra Modi in the matter. The teachers are protesting against the delay in announcement of results by the NIOS.