Cassidy entered the hospital earlier this week and is now in need of a liver transplant, his rep said.
In February, Cassidy revealed he has dementia, prompting him to retire from touring.
The publication claims he "needs a liver transplant soon or he could die".
His family are now said to be at the hospital to be by his side as his condition worsens. "I want to focus on what I am, who I am and how I've been without any distractions". I want to enjoy life'. He made 10 albums for The Partridge Family, as well as more than eight solo albums and 24 singles.