Lok Janshakti Party chief Chirag Paswan has thanked Prime Minister Narendra Modi and Home Minister Amit Shah for inquiring about the health of his father, Union Minister Ram Vilas Paswan, who is in intensive care and undergoing treatment at a Delhi hospital.
"Many times today Prime Minister called to ask after papa's condition. Honourable Prime Minister also spoke to the doctors involved in his treatment. Thank you," Mr Paswan junior tweeted in Hindi.
Hours later he tweeted again: "I express my gratitude to respected Home Minister Amit Shah for taking care of my father's health. He himself has not been well for a few days (Mr Shah is recovering from post-Covid complications) but, despite that, thank you for showing affection towards me".
Mr Paswan senior has been admitted for a "routine health check-up" his son said had been delayed because of the workload during the Covid pandemic.
The tweets come amid a straining of ties in Bihar between the LJP and Chief Minister Nitish Kumar's JDU ahead of Assembly elections due by November.
Chirag Paswan has made no secret of his chief ministerial ambitions and has not shied away from taking pot shots at Nitish Kumar - on everything from floods to COVID-19 and even the Sushant Rajput case.
He has, however, been cautious about attacking the BJP, with many believing he is reluctant about endangering his, at present, stable political career while the BJP remains in power at the centre.
The BJP, meanwhile, is trying to hold the three parties together with elections right around the corner. Seat-sharing talks between them, as well as other members of the NDA, are ongoing.
However, Mr Paswan junior has delayed his visit to Bihar because of his father's illness. In a letter written on Sunday, he said his father had urged him to return, but he felt it not right while he was in hospital.
He also said no discussion had been held so far over seat-sharing.
Mr Paswan junior's criticism had cast doubts over the LJP continuing within the NDA.
Earlier this month, though, in an apparent U-turn, he said: "I have no problem with Nitish Kumar as the face of the NDA", although further comments on the matter suggested he was still not entirely happy.
"... I am okay with any Tom, Dick or Harry chosen by the BJP," he said.
Last week Mr Paswan junior urged the BJP to allocate more seats to him than the JDU, which won 71 of the 101 seats it contested in 2015. The LJP fought 42 and won just two.
In Lok Sabha polls last year the JDU and BJP fought 17 seats each, leaving the remaining six to the LJP.
Elections for the 243-member Bihar Assembly are due by November; the current Assembly's tenure ends November 29.
With input from ANI