Parrikar, 63, who is suffering from a pancreatic ailment, was admitted to the All India Institute of Medical Sciences (AIIMS) on January 31. He has been in and out of hospitals in Delhi, New York, Mumbai and Goa since last year.
"The ailment he has got has no cure. There will be no political crisis till Manohar Parrikar is in chair. But the day he steps down on his health ground or something happens to him, there will be a political crisis. He is very unwell," said Lobo, who is a senior BJP leader and represents Calangute Assembly constituency. "He is still living and working with God's blessings," he added.
Parrikar heads a coalition government, which is supported by the Goa Forward Party (GFP), the Maharashravadi Gomantak Party (MGP), and three Independent MLAs. Sources at the AIIMS Saturday said Parrikar's condition was stable.
Veteran BJP leader L K Advani, Congress president Rahul Gandhi and Army Chief General Bipin Rawat had met the ailing chief minister in Goa earlier to enquire about his health.
Earlier in the day, on the occasion of the World Cancer Day, Parrikar said in a message that the human mind can overcome any disease. Last week, Parrikar, with a tube inserted through his nose, had presented the state in the Goa Assembly.
Lobo had earlier demanded that Parrikar step down on health grounds, as he has been absent from office for long. The MGP had in the past threatened to pull out from the BJP-led government on various issues including crisis in the mining industry.
The party has been demanding that senior leader Sudin Dhavalikar be appointed as the chief minister.