The vice-president said that "Thackeray made significant contributions to public life in Maharashtra".
"Throughout his life he remained committed to well-being of the people of Maharashtra," Ansari said.
Congress spokesperson Rashid Alvi said Thackeray had an important role in politics of Maharashtra. Congress general secretary Digvijaya Singh said that Thackeray has left a "legacy for the Shiv Sena".
Digvijaya Singh conveyed his condolences to Bal Thackeray's son Uddhav, and described the Sena supremo as his personal friend.
Bharatiya Janata Party (BJP) spokesperson Shahnawaz Hussain said Thackeray's demise was a loss to the National Democratic Alliance and "a blow to Maharashtra and the NDA".
"It has ended an era. Till the time he lived, he lived like a lion. A leader like him is born after ages. The void can never be filled. His death has hurt the entire country," Hussain said.
Union Agriculture Minister Sharad Pawar, whose Nationalist Congress Party (NCP) is an adversary of the Shiv Sena in Maharashtra, said Thackeray took decisions openly and stuck to his convictions.
Congress leader and union Home Minister Sushilkumar Shinde said Thackeray "emerged as a storm in Maharashtra politics after the Communist party withered".
Shinde, former chief minister of Maharashtra, said Thackeray had supported him in some decisions he took while serving the state.