Former Prime Minister Manmohan Singh on Thursday expressed his support for the passage of the Centre’s four Goods and Services Tax Bills and asked his fellow Congress Rajya Sabha members to refrain from calling for amendments. Describing the legislation as a “game-changer”’, Singh asked his party colleagues to “maintain consensus and federal agreement.” His statements helped the smooth passage of the Bills in the House where the Bharatiya Janata Party is in the minority. After the Bills were passed, Finance Minister Arun Jaitley walked up to Singh and shook his hands.

Singh’s advisory to Congress members prompted party MP Jairam Ramesh to refrain from moving amendments proposed. “Former PM Manmohan Singh has taken this approach in the spirit of consensus and in respect of the federal structure,” The Times of India quoted Ramesh as saying.

Asked to comment on the Bharatiya Janata Party’s opposition to the GST reforms when they were introduces by the Congress-led United Progressive Alliance, Singh said “let bygones be bygones,” NDTV reported. He told the news channel that he was happy with the passing of the “historic Bill”. The Congress was opposed to the Bill being passed as a money bill instead of a financial bill.

“We should not assume that there will be no difficulties,” Singh said later. “There must be a constructive spirit. There must be cooperation between the federal government and the state governments to resolve those outstanding issues.”

The Rajya Sabha’s approval now paves the way for the Centre to implement the new tax regime by July 1.

The Bills were passed in the Lok Sabha on March 29 after Jaitley had tabled them Bill in the Lower House on March 27, hoping to have them passed with consensus in Parliament during the ongoing Budget Session. The GST, which seeks to overhaul India’s complicated taxing system by replacing 17 different taxes with a single levy, was passed by the Rajya Sabha on August 3. The Union Cabinet had approved the Bills on March 20.

The GST has a four-slab structure – 5%, 12%, 18% and 28%. The government has set the maximum GST rate at 40% and introduced provisions for an anti-profiteering authority and arrests for evading taxes.