Thiruvananthapuram, March 26 -- Congress leader Rahul Gandhi said on Wednesday that the lack of progress in the corruption cases filed against Kerala chief minister Pinarayi Vijayan was the best proof of collusion between the CPI(M) and the BJP. Gandhi made the claim while addressing a massive election rally of the Congress-led United Democratic Front (UDF) in Kozhikode via video-conferencing. Though Gandhi was slated to visit Kozhikode on Wednesday, he skipped the trip after his mother Sonia Gandhi was hospitalised in Delhi. AICC chief Mallikarjun Kharge flew down to Kerala in Gandhi's absence. "Why are corruption cases against the CM not going anywhere? This is the best proof of collusion between the BJP and LDF," Gandhi claimed. Meanwhil...