When Prime Minister Narendra Modi's party won a landslide in India's last general election, in 2014, it grabbed almost all the parliamentary seats in the heartland states of Madhya Pradesh, Rajasthan and Chhattisgarh.
But his Bharatiya Janata Party (BJP) could be about to lose power in the three states - results of recent state assembly elections will be announced from early on Tuesday - which would raise huge questions over Modi's bid for re-election in polls due by May.
Analysts say a big loss for the BJP in the states would indicate rural dismay and could help unite opposition to Modi, whose personal popularity remains high despite criticism he has not been able to keep a promise of creating jobs for young people and improving the lot of farmers.
Indian share markets and the rupee have already turned nervous, falling on Monday, the first trading day since exit polls said the BJP would lose Rajasthan, with the other two going down to the wire.
Equity analysts said the surprise resignation of the Reserve Bank of India governor, Urjit Patel, late on Monday after a long tiff with the government could send the markets crashing.
"As the three erstwhile BJP states have a large agrarian population, the BJP's drubbing could be interpreted to mean that farm unrest is real, and the much vaunted increase in farm minimum support prices haven't yielded material political dividends," Nomura said in a research note.
"A rout of the BJP on its home-ground states should encourage cohesion among the opposition parties to strengthen the non-BJP coalition for the general elections."
The central states of Madhya Pradesh and Chhattisgarh, and the western state of Rajasthan, together account for 65 of the 543 seats for the lower house of parliament. Several research firms have said markets could fall sharply if the BJP loses all the three states currently held by them.
Regional parties are likely to retain two other smaller sates, Telangana in the south and Mizoroma in the northeast, that also report results on Tuesday, the polls show.
The main opposition Congress party, led by Rahul Gandhi of the Nehru-Gandhi dynasty, has been trying to form a coalition of various regional groups, some headed by experienced firebrand, ambitious politicians.
Congress has already said it would not name Gandhi, who is seen as lacking experience, as a prime ministerial candidate, keeping in mind the "aspirations" of other opposition parties.
Leaders of 21 opposition parties, including Gandhi and former Prime Minister Manmohan Singh, also of the Congress, met in New Delhi on Monday as they sought to strengthen their stand against Modi.
In a likely boost for the opposition, a federal minister, Upendra Kushwaha, said on Monday he would pull his small party out of the BJP-led coalition.
Media has speculated he would join Modi's opponents ahead of the general election.
The BJP says the planned opposition alliance would be fractious, would struggle to find focus and would be riven by competing interests.
The BJP has also cast doubt on the exit surveys, saying they have underestimated its performance in the three states.
While analysts have been warning it would be a mistake to rule out BJP wins in all main Hindi-speaking states, they have also warned that the party has lost the narrative to an extent.
Sriram Karri, a political strategist and author, said the BJP government was losing its sheen because it was afraid to take "big bold moves," like including fuel in a unified goods and services tax and cutting income tax.