RJD leader Tejashwi Yadav boycotted Nitish Kumar's Monday evening swearing in ceremony but joined the LJP's Chirag Paswan in congratulating the JDU chief after he was confirmed as Bihar Chief Minister for a sixth time.
However, like Mr Paswan, Tejashwi Yadav also took the opportunity for a dig at the JDU boss and praised Nitish Kumar for being "nominated" to the post - to remind him, once again, that his party had performed well below par and that he had only retained his job because the BJP opted not to exercise its newfound "big brother" status to install one of its own as chief minister.
"Best wishes to respected Nitish Kumarji for being 'nominated' Chief Minister. I hope, instead of pursuing his ambitions, he will fulfill aspirations of the public and the NDA's promise of 19 lakh jobs, and will make employment, health, income generation, irrigation his priority," Mr Yadav tweeted.
Tejashwi Yadav led a strong campaign in the recently concluded Bihar election and his party emerged as the single-largest with 75 seats. He ran on a platform that targeted Nitish Kumar on several issues, including lack of development in Bihar and mismanagement of the Covid crisis.
The RJD leader's promise of 10 lakh government jobs - for a state where unemployment levels are among the worst in India - made particular headlines, with thousands drawn to Mr Yadav's rallies.
A visibly irritated Nitish Kumar, facing a strong anti-incumbency wave, hit back with personal attacks. He dismissed Tejashwi Yadav as inexperienced and the claim of 10 lakh jobs as "bogus". He also referred to the 15-year rule of Mr Yadav's parents - Lalu Yadav and Rabri Devi.
The BJP, though, quickly sensed jobs was a talking point with voters, especially when the Covid lockdown and migrants crisis had left the poorest deprived of livelihoods and struggling to survive, and, despite Nitish Kumar's caustic comments, promised 19 lakh jobs to Mr Yadav's 10 lakh.
Nitish Kumar was also attacked over his "ambition" to stay in power - this time by Chirag Paswan, who claimed the JDU chief would stand "with hands folded and head bowed" before Mr Yadav.
After a spirited campaign that appeared to leave Mr Kumar and the JDU on the brink of defeat - exit polls predicted a win for the opposition - the ruling JDU-BJP bounced back to claim victory.
The difference was a strong showing by the BJP, which claimed 74 seats to the JDU's 43 to prop up Nitish Kumar and take the NDA over the finishing line. The win was a reversal of fortunes - in 2015 the JDU had 71 and the BJP 53 - and left Mr Kumar's hopes in the BJP's hands.
The BJP had stressed that Mr Kumar would remain in the top post if the NDA was re-elected. However, the margins triggered speculation he might be dropped.
Last week Nitish Kumar said the decision on a chief ministerial candidate would be taken by the NDA - a statement seen as an indication of nervousness. On Sunday, though, the newly-elected NDA legislators met and named Nitish Kumar as their Chief Minister.
The BJP does, however, have two deputies from their ranks compared to the one in the last term. Sushil Kumar Modi has been replaced by Renu Devi and Tarkishore Prasad.