As far as the Yadavs are concerned, Rabri is the proxy candidate for Lalu Prasad, who is not in the fray after being convicted in a multi-crore fodder scam and was debarred from contesting the polls.
In last polls in 2009, Lalu Prasad defeated Rudy by 50,000 votes. Then JD-U was in then in alliance with BJP.
Saran votes Wednesday, marking the penultimate round of Lok Sabha elections that began April 7 and end May 12. The results will be announced May 16.
Yadav and Rajputs have almost similar number of votes and widely seen as traditional rival in electoral politics.
"Yadavs are solidly behind Lalu and major chunk of Rajputs are supporting Rudy on caste ground," said Ranjeev, a political watcher.
With Yadavs and Rajputs supporting their castemen in polls, both Rabri and Rudy are eyeing support of other upper castes, particularly sizeable landed Bhumihar, extreme backward castes (EBCs), Mahadalits and Muslims.
Muslims, who have nearly 2 lakh votes, can play important role to decide polls outcome as in past.
Like elsewhere in the state, Muslims say that only Lalu can stop BJP's prime ministerial candidate Narendra Modi.
"We are with Lalu because he is in a position to stop Modi and defeat BJP in Bihar," said Siraj Ansari in Chapra town.
BJP workers said that Modi wave has given an advantage to Rudy.
"Even young Yadavs are supporting Modi and it provided us a big hope that they will vote for Rudy, a rare thing thanks to Modi impact," said Mahesh Singh, a BJP worker.
Singh said if young Yadavs support for Modi translates into votes for the BJP, Rudy will have clear edge.
"...Rudy's luck is dependent on the split of young Yadavs. If it happens, then there is a surprise in store," he said.
RJD leader Kanchal Bala, who is camping here with Rabri, told IANS that Modi tried to woo Yadavs by playing mythological Yadhuvanshi card.
"It appears Modi failed to woo Yadavs despite playing Yadhuvanshi card," she said.
RJD's another hope is the way Bhumihar votes.
Outside Saran, they have been supporting Modi. But here they may support Lalu because of their traditional rivalry with Rajputs.
Sensing the electoral challenge, Lalu has worked overtime as his prestige is at stake here. In past he had won his home turf four times, beating Rudy twice in succession.
Not just Lalu and Rabri, even their elder daughter Misa Bharti and younger son Tejaswi Yadav have vigorously campaigned, addressed election meetings and held roadshows.