Singh was admitted to AIIMS on Monday after testing Covid positive.
"Followed up on Dr Manmohan Singh Ji's health with the medical team attending to him at AIIMS, Delhi. His condition is stable. Best possible care is being provided to him. We all pray for his quick recovery," Harsh Vardhan tweeted.
Congress interim President Sonia Gandhi also wished him a speedy recovery. She said, "I am deeply concerned to learn that Dr. Manmohan Singh is unwell & has been hospitalised. On behalf of all of us in the Congress Party I send my good wishes to him for a speedy & complete recovery."
"My prayers are with Manmohan Singh ji and his family today, and my deepest respect. May he fight this scourge with all his might and get well soon," tweeted Congress General Secretary Priyanka Gandhi Vadra.
Prime Minister Narendra Modi has also wished him a speedy recovery.