75-year-old Rau was found unconscious on Monday morning in the bathroom of Jodhpur House in New Delhi and was immediately taken to the hospital, a state government spokesman said.
"We have not discussed the matter in our party," the MPCC chief said.
A commemorative stamp of late Joachim and Violet Alva was released by President Pratibha Patil in New Delhi today, coinciding with the birth centenary year of the couple.
Earlier, three Rane supporters quit their assembly seat which they had won as Sena nominees in 2004 polls, and had joined Congress.
Nirupam said he would take a decision on his new political address soon.
Within two or three days, a Congress team would discuss seat sharing arrangements with the NCP. The task is to be finished by the end of August.
Congress Vice-President Rahul Gandhi had brought in the United States style 'primaries' with much fanfare to empower grassroot leaders to fight the Lok Sabha elections.