A slew of Union ministers resigned late Thursday evening, all but cementing rumours of an impending reshuffle of Prime Minister Narendra Modi's council of ministers that sources said could happen as early as today, or by Saturday; the PM leaves for a BRICS summit in China on Sunday.

Minister for Water Resources Uma Bharti, and Nirmala Sitharaman, Minister of State for Commerce, Industry and Corporate Affairs. and Rajiv Pratap Rudy, Minister with independent charge of State Skill Development and Entrepreneurship stepped down from their positions.

Dharmendra Debendra Pradhan, minister of state for petroleum & natural gas, and Piyush Goel, MoS for power, coal, and new & renewable energy are likely to be elevated to cabinet rank.

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Some more ministers are also said to have offered to resign, including Minister of Micro and Small Enterprises Kalraj Mishra, Minister of State for Human Resource Development Mahendra Nath Pandey, and Minister of State for Agriculture Sanjiv Baliyan. Mishra has crossed the age of 75 and is tipped to get a gubernatorial posting.

Shah, who has already had several meetings over the past two weeks with several cabinet ministers, held an unscheduled meeting with Prime Minister Narendra Modi just before Rudy's resignation.

Finance Minister Arun Jaitley suggested as much when, asked by reporters for how long he would continue to hold the twin charge of Defence Ministry, he quipped, "At least I hope not very long." He is expected to shed at least one of his portfolios; any new defence minister will have to leave for Japan early next month to attend the annual global defence ministers' conference

Delhi's political circles were rife with speculation that some chief ministers of BJP-ruled states may also move to Delhi to augment the Union Cabinet. The presence of Rajasthan CM Vasundhara Raje in the national capital on Thursday to meet with several central leaders fuelled the rumour mill. Though Rail Minister Suresh Prabhu has also offered to resign, he is likely to be shifted to some other ministry, sources said.

Union Road and Transport Minister Nitin Gadkare is likely to replace Prabhu, while Agriculture Minister Radha Mohan Singh is also likely to be shifted to some other ministry. Faggan Singh Kulaste, Minister of State for Health and Family Welfare, could find himself out in the open.

The buzz is also that the Union government may accommodate leaders like Bhupendra Yadav, BJP's in-charge of Gujarat, with an eye on elections in the state later this year. Party heavyweight Ram Madhav, who has been instrumental in the BJP's gains in the Northeast, is also being tipped for a Cabinet berth.

Meanwhile, Sitharaman is likely to return for party work – she is an assistant in-charge of the Gujarat Assembly elections, the team for which is being led by Arun Jaitley.

Bihar BJP leader Rudy was one of the first to put in his papers, signalling the process has started.

The minister's exit is expected to pave the way for at least two Janata Dal (United) leaders who are expected to join the Cabinet in the wake of that party rejoining the National Democratic Alliance (NDA).

Sources suggested that Rudy's exit is a way of maintaining regional balance in the Cabinet following JD(U)'s re-entry into the NDA fold. Cabinet portfolios are a time-honoured method of political reward; the same is likely to be extended to reward Nitish Kumar's JD(U), which is back to sharing power with the BJP in Bihar after a bitter break-up with Lalu Yadav's RJD and the Congress in July.

The expansion of the council of ministers is also to fill vacancies caused by the sudden demise of environment minister Anil Madhav Dave and the return of former defence minister Manohar Parrikar to Goa state politics. The election of M Venkaiah Naidu as vice-president has also deprived the cabinet of a key minister.

Some ministers are holding additional portfolios of urban development and information & broadcasting after Naidu's elevation. The Environment ministry was also reassigned to Harsh Vardhan after Dave's untimely death.

PM Modi has a two-day window for the reshuffle, following which he will be gone for at least two days. During that two-day window, the Rashtriya Swayamsevak Sangh, which is said to have some say in ministerial allocations, is holding a three-day annual coordination meeting starting September 1 in Mathura.

The conclave will be attended by several top BJP ministers to deliberate preparations for 2019 elections critically reviewing the work done by both the Modi government and the organisations and find out ways how to bring synergy between the two for reducing friction and maximising gains.

Sources said the cabinet reshuffle will now depend on whether time can be squeezed out from the tight schedule on Friday and Saturday.