THE Left-Democratic Manch (LDM), Assam-a common platform of 10 political parties comprising of the CPI (M), CPI, CPI (ML), AAP, SP, NCP, RCPI, Janata Dal(S), LDP and Asom Sangrami Mancha, staged a massive 'sit-in-demonstration' at Jantar Mantar in New Delhi on December 28.