But Tuesday’s bonhomie — last seen when the two opposed FDI in multi-brand retail — was unexpected.
When Sugata Roy of Trinamool Congress raised a point of order after finance minister P Chidambaram introduced the bill, Left MPs stood up in his support.
Trinamool MPs reciprocated by rushing into the well, where Left members were gathered seeking withdrawal of the bill and eventually their joint sloganeering led to an adjournment.
In between the two adjournments they forced, the MPs from the two parties could be seen strategising together on how to force the government to accept their demands, especially on withdrawing provision to allow banks to invest in forward contracts.
They came together again when parliamentary affairs minister Kamal Nath approached a Left leader and the entire group agreed with the solution offered by CPI's Gurudas Dasgupta.
Roy described Dasgupta as guru of the banking sector and even quoted him. Khagen Das of CPM referred to Roy several times in his intervention and even the speech content from the two parties was similar.
Dasgupta saw "nothing wrong" in this unusual convergence saying they have come together to oppose a farce being perpetuated by the government in the name of economic reforms.