"Ghosh has been taken off ventilator support. He is conscious, haemodynamically stable and following commands," doctors attending to him at Apollo Hospital said.
However, the 94-year-old leader remains critical and the prognosis guarded, they said.
Ghosh was admitted to the intensive care unit of the hospital over a week ago due to age-related illness.
He continues to be on broad spectrum antibiotics, in-line nebulisation and nutrition is being maintained by Ryles tube feeding, one of the doctors said.
Ghosh took over as state secretary of Forward Bloc in the late 1940s and has been re-elected to the post for the past seven decades making him the longest serving leader at the post in any party.