Somnath Chatterjee, a 10-time parliamentarian, died on Monday morning in Kolkata.

Highlights Somnath Chatterjee was the first key CPM leader to defy the party

He was expelled for sticking to a non-partisan stand on Indo-US nuke deal

In his life, he only lost one election -- to Mamata Banerjee in 1984

Former Lok Sabha Speaker Somnath Chatterjee spent the last few years of his life in seclusion, expelled by the CPM despite representing the political party in Lok Sabha for almost 40 years, for sticking to a non-partisan stand during a critical moment in parliament's history.

He was the first key leader to defy the party. Even his close associate and Bengal's all-powerful, five-time Chief Minister Jyoti Basu had fallen in line when the CPM refused to permit him to become Prime Minister.

Mr Chatterjee -- a 10-time parliamentarian -- died this morning in Kolkata after being in and out of hospital for the last two months. He had been admitted to Belle Vue hospital on 8 August.

A towering figure in the party and its only Speaker in Lok Sabha, Somnath Chatterjee was expelled during the tussle between the CPM and the UPA government led by Manmohan Singh over the Indo-US nuclear deal.

The Communist Party of India (Marxist), which did not want the deal, had withdrawn support from the government in July 2008. It also wanted Mr Chatterjee to step down before a two-day special session of the Lok Sabha beginning July 21, and vote against the government during the trust vote.

But the UK-trained barrister had decided to see the trust vote through. He turned down all requests from his party and its all-powerful leader Jyoti Basu to quit, maintaining that as Speaker, he was above partisanship and party politics.

A month later, he was expelled for "seriously compromising the position of the party". Mr Chatterjee later called it "one of the saddest days" of his life. He, however, continued till the end of his term with support from the ruling alliance.

In 1996, Mr Chatterjee was one of the first recipients of the newly instituted "Outstanding Parliamentarian" award. Even his critics admitted that he was a good Speaker and a fair umpire.

After his expulsion, Mr Chatterjee's constituency Bolpur became reserved for scheduled caste candidates, which meant despite his huge popularity, he could no longer contest from there.

When Sitaram Yechury was elevated within the CPM in 2015, there was a buzz about bringing back Somnath Chatterjee into the party, which by then was in the doldrums after Mamata Banerjee's sweeping victory four years before.

Mr Chatterjee, however, admitted in an interview that he refused the offer since he did not deserve to be expelled in the first place.

Born in Assam's Tezpur in 1929, Somnath Chatterjee had joined politics in 1968 and became a member of the Lok Sabha in 1971. In his life, he only lost one election -- to Mamata Banerjee in 1984, which made her the youngest parliamentarian at the age of 29 years.