Former Union minister Raj Kumar Singh’s resignation on Saturday landed like a jolt inside the BJP’s Bihar unit.

Hours after being served a showcause notice that declared he was being “suspended” for “anti-party” activities, Singh walked out of the party and made the confrontation public.

Singh released his resignation letter addressed to BJP national president Jagat Prakash Nadda, announcing that he was giving up his primary membership.

He followed it with another letter, this time to Arvind Sharma, the state headquarters in-charge who issued the notice, informing him that the resignation had already been sent to the national leadership.

In both letters, Singh claimed his utterances aimed at "curbing corruption and criminalisation of politics seem to have made some people uncomfortable".

The showcause was not restricted to Singh.

Sharma dispatched identical letters to MLC Ashok Kumar Agrawal and Katihar mayor Usha Agrawal for campaigning for their son Saurabh, who contested from Katihar on a Vikassheel Insan Party ticket against BJP’s sitting MLA and former deputy chief minister Tarkishor Prasad.

Singh’s clash with the BJP leadership has been building for years.

The former home secretary, has repeatedly criticised senior leaders including Bihar’s deputy chief minister Samrat Choudhary for their alleged involvement in criminal cases.

After losing the Ara Lok Sabha seat last year, a seat he held for two terms, Singh continued to take positions that put him at odds with the leadership.

His opposition to the state government’s deal with the Adani Group for a power plant in Bhagalpur further widened the gap.