However, on July 23, 2008, he was expelled from the CPI-M because he refused to step down as Speaker after the party withdrew support to the United Progressive Alliance government.
A CPM release said, "The Politburo of the Communist Party of India-Marxist has unanimously decided to expel Somnath Chatterjee from the membership of the party with immediate effect. This action has been taken under Article XIX, clause 13 of the Party Constitution for seriously compromising the position of the party."
West Bengal CPI-M secretary Biman Bose said "Chatterjee may have acted according to the Indian Constitution but the party constitution is supreme in the case of party members."
For Chatterjee, the expulsion was "one of the saddest days" in his life. He suggested that future speakers should resign from their parties while serving in that office to help ensure its non-partisan standing.
Describing his five-year tenure as Lok Sabha Speaker as a "great opportunity", Somnath Chatterjee said the worst moment during his term was July 22, 2008 when MPs displayed wads of currency notes during the Trust Vote debate.
"It was a great opportunity...I never expected it but I got it," Chatterjee told reporters on the Parliament premises on Thursday on his innings as Speaker.
Image: Prime Minister Manmohan Singh, the then President A P J Abdul Kalam and Somnath Chatterjee arrive at Parliament on the opening day of the Budget session in New Delhi on February 23, 2007. | Photograph: B Mathur/REUTERS
Also see: Somnath takes a dig at MPs