At a rally in Chapra, 75 km from here, addressed by leaders of RJD, JD(U) and Congress for an Assembly bye-election earlier in the day, Prasad said he has not seen a "weathercock" like Paswan who changes tack to suit his own political requirements without carrying a baggage of ideology.
"He (Paswan) is a rank opportunist who switches sides at the drop of a hat," Prasad said.
An angry Paswan hit back at the RJD supremo asking him to explain his alliance with his bitter foe-turned-friend Nitish Kumar.
"Instead of calling me a 'weathercock', Prasad should explain as to why he had to join forces with senior JD(U) leader Nitish Kumar whom he had been denouncing with choicest words for past 20 years," he told reporters in Patna.
"If I have been a weathercock, what is he as he joined hands with Nitish Kumar after attacking him for 20 years," he asked before leaving for Hajipur to campaign for BJP.
During campaigning for the bypolls in ten Assembly seats, Prasad has been ridiculing the LJP leader as a "habitual turncoat" and a "weathercock".