Yadav's victory, that took RJD's tally of Lok Sabha seats to 24 out of a total of 40, demolished all hopes the NDA might have had of stalling the RJD-led secular alliance's juggernaut with its tally remaining stuck at 11.
Of the 24 seats in RJD's kitty, Palamu and Chatra are in Jharkhand.
Rudy is the seventh minister in the erstwhile Vajpayee government from Bihar to have lost the 2004 general elections the others being Sharad Yadav, C P Thakur, Syed Shahnawaz Hussain, Hukumdeo Narain Yadav, Sanjay Paswan and Digvijay Singh.
With Yadav's win in Chapra, the secular alliance comprising apart from RJD, the Congress and Ramvilas Paswan's Lok Jan Shakti party, shot up to 29. While the Congress won three of the four seats it contested. The LJP bagged four of the eight it fought. The RJD, which was alloted 26 seats as part of the electoral arrangement, put up a spectacular showing winning 22.
NDA constituent JD-U, which had contested 24 seats, could manage to win only six and BJP bagged five trying its luck in 16 constituencies.
The NDA had won 30 of the 40 seats in Bihar in the 1999 general election with JD-U garnering 18 and BJP 12.
Even JD-U strongman and former Railway minister Nitish Kumar, who had contested from both his traditional Barh seat as also Nalanda, lost Barh to former Bihar minister Vijay Krishna of RJD. The only saving grace was that he won from Nalanda. Kumar had won from Barh five times in a row.
However, NDA Convenor and JD(U) President Geroge Fernandes, who had vacated Nalanda for Kumar to try his luck from Muzaffarpur seat for the fifth time after a hiatus of nearly 13 years, managed to scrap through by a narrow margin of little over 12,000 votes.
Interestingly, the RJD candidates emerged victorious in all the three constituencies -- Chapra, Siwan and Bettiah -- where repoll was held in the wake of reports of large-scale irregularities after the government formation at the Centre.
While the EC had ordered repoll in 429 booths in Bettiah and 193 in Siwan, it had countermanded the election to Chapra seat ordering repoll in all the 1157 polling stations on May 31.
Both Laloo and Rudy had won the Chapra seat twice earlier with the RJD chief emerging victorious in 1977 and 1989 and the BJP leader in 1996 and 1999.
Laloo, who won the Madhepura seat earlier defeating JD(U) leader Sharad Yadav, after the repoll in Chapra had said he would take a decision on which seat to retain after giving the issue a ''proper thought.''