Babul Supriyo has also quit ahead of the reshuffle.
Union Health Minister Dr Harsh Vardhan and 11 other ministers - including Babul Supriyo - have resigned, sources said today, hours before Prime Minister Narendra Modi's mega cabinet reshuffle.
Education Minister Ramesh Pokhriyal Nishank and Labour Minister Santosh Gangwar were the first to quit the Union Cabinet today.
Other ministers who have quit are Sadananda Gowda, Debashree Chaudhuri, Sanjay Dhotre, Ratan Lal Kataria, Minister of State for Health Ashwini Chaube, Pratap Sarangi, and Rao Saheb Dhanve Patil.
Thawarchand Gehlot, 83, who was Union Minister for Social Justice and Empowerment, will take over as Governor of Karnataka.
The resignation of both Health Ministers comes as the government battles criticism of its handling of the second wave of Covid in April-May.
Mr Nishank and Santosh Gangwar have reportedly given health reasons in their resignation letters.
According to Labour Ministry sources, Mr Gangwar paid for his ministry's poor handling of the migrants and jobs crisis in the pandemic.
The Supreme Court had severely indicted the ministry for its failure to set up a portal for registering unorganized and migrant workers. "The lackadaisical attitude of the Ministry of Labour is unpardonable," the Supreme Court had said on June 29.
A detailed performance review was carried out by the Prime Minister and top leaders over the past few weeks.
Among likely names up for elevation are Anurag Thakur, Purshottam Rupala and GK Reddy. All three were seen arriving at PM Modi's residence along with would-be ministers expected to be sworn in later today.
Jyotiraditya Scindia, Sarbananda Sonowal, Narayan Rane, Bhupendra Yadav and Meenakshi Lekhi are set to join the government. They were among ministers-to-be who visited PM Modi's residence ahead of the revamp.
This is the first revamp of the Council of Ministers since PM Modi started his second term in May 2019.