Subba, who fell ill yesterday in Tezpur, was airlifted and admitted to a private hospital here and was today shifted to a hospital in Delhi, doctors attending on him said.
Subba has high blood pressure but his condition was stable, they said.
Meanwhile, Toppo, who too, has been suffering from high blood pressure and was admitted to a private nursing home in Tezpur yesterday.
He was today released after his condition stabilised, party colleague and former minister Kamala Kalita said.
Also Read
Subba, a three-time Congress MP from the constituency, had lost to Toppo in the last Lok Sabha polls.
The party denied him ticket as court cases were pending against him but he decided to contest as an independent with Assam's principal party, the AIUDF, extending support to him.
Tezpur goes to poll in the first phase on April 7.