"For some time, there has been a tradition in the party that those who attain the age of 75 voluntarily retires from the post. I will attain the age of 75 in November," Anandiben, Gujarat's first woman chief minister and a former teacher, said in a Facebook post on Monday.
BJP president Amit Shah, who has had a running battle with Anandiben, said in Delhi that he had received her letter, which would be placed before the party's parliamentary board. "In principle, the resignation has been accepted," a source close to Shah said.
For the past few months, speculation has been rife about the departure of Anandiben, whose innings has been rocked by the Patel agitation for reservation, discontent in industry and dissidence in the BJP.
The flash point was the ongoing Dalit rebellion, ignited by a brutal flogging by purported cow protectors or gau rakshak, that became a national issue, sending ripples in Uttar Pradesh where the BJP is facing a litmus-test election next year.
Gujarat, the jewel in Modi's crown, is also set to go to polls in 2017. Beneath the social embers other flames too were leaping to the surface, fanned by discontent among traders and farmers. "Things are getting out of hand," a Gujarat BJP leader conceded, adding, "If Modi does not act now, Gujarat would go from us."
The so-called Gujarat model was one of the biggest showpieces on Modi's 2014 road show, the magic potion to cure all the ailments that afflicted the country during the UPA decade.
Sources said the "course correction" in Gujarat was undertaken keeping in mind the assessment that any setback in Uttar Pradesh, where the BJP made astonishing gains in the 2014 general election, would be a body blow to Modi.
Similarly, a defeat in Gujarat - a state the BJP has never lost since 1995 but for a short and forgettable spell of a coalition government - can signify a damaging reversal for Modi and Shah.
Sources said Anandiben further damaged her case three days ago when she appointed J.N. Singh as the Gujarat chief secretary - a choice that apparently did not go down well with Modi.
Singh is said to be close to Gujarat Congress leader Shankersinh Vaghela, Modi's arch adversary who had rebelled and left the BJP. Singh was textiles commissioner when Vaghela was textiles minister in the UPA regime.
The sources said that in choosing Anandiben's successor, Modi would weigh a nominee's ability to salvage Gujarat from the wreckage left by a myriad of caste conflicts and address the concerns of medium and small enterprises.
Indeed, Shah said in Delhi that Anandiben's successor would need "adequate" time to prepare for the next Vibrant Gujarat summit in January 2017. The business summit was conceptualised by Modi as a clone to the Davos jamboree.
Asked if Shah could return to Gujarat to reset the pieces on a chessboard gone awry, a source, without ruling it out straightaway, said: "That depends on what assessment the PM has about Shah's ability to deliver Uttar Pradesh in the state polls."
Shah, who had unbridled control over the BJP organisation when Modi was chief minister, is said to be rooting for the Gujarat party president, Vijay R. Rupani, to take over from Anandiben.
Sources said Modi "may not" endorse Shah's pick "that easily", if only to quash a perception that the party chief had catalysed Anandiben's exit.
Rupani was appointed the Gujarat BJP president after a hard-fought battle between Shah and Anandiben, in which the party's national boss triumphed. From that moment on, Shah had signalled that Rupani would have to be treated on a par with the chief minister.
Rupani, who remains a minister in Anandiben's cabinet despite holding a party post, facilitated Shah's stranglehold over the state apparatus and minimised her interventions in party affairs.
Among those in the "neutral" slot is health minister Nitin Patel. "But I wonder if he would let one Patel be replaced with another and aggravate caste feelings again," a source said.
The source said that in order to "counter" the fallout of the Dalit uprising, a senior Dalit minister, Ramanlal Vora, could be elevated as deputy chief minister.
In Delhi, sources claimed that age was the sole factor that led to Anandiben's decision to exit. They pointed to the departure of Najma Heptullah from the Union ministry after she turned 75.
But Anandiben, picked as the chief minister by old political confidant Modi before he headed to Delhi in May 2014, had run into turbulence early on in her innings.
In the rural elections in December last year, the BJP lost 23 of the 31 district panchayats and the Congress wrested 22 for the first time in 20 years.
Controversial land deals linked to Anandiben's daughter are also considered a liability, especially when the Aam Aadmi Party is trying to make inroads in Gujarat.
Before quitting, Anandiben played the last dice, unveiling a slew of populist measures that included a promise of a pay hike for government employees, withdrawal of police cases against the Patel agitators and exemption of cars and small vehicles from highway toll. "Every one of her move will leave Gujarat cash-strapped," a BJP official said.
When Modi was chief minister, his office used to receive real-time footage from key toll collection centres so that he could keep up to speed on the amount netted each day.
-The Telegraph Calcutta