The Congress on Tuesday accused Asaduddin Owaisi's AIMIM of undermining its vote base in Bihar's crucial Seemanchal region to help the BJP. Adhir Ranjan Chowdhury, a senior Congress leader, described Mr Owaisi as a "vote-cutter" and asked secular parties to be "alert".
"BJP's tact of using (Asaduddin) Owaisi sahab's party in the Bihar elections has succeeded to an extent. All secular parties should be alert about vote-cutter Owaisi sahab," he was quoted as saying by news agency ANI.
Mr Owaisi's party had fielded 20 candidates in the region, which has a sizeable Muslim population. The JDU-led National Democratic Alliance (NDA) is leading in several seats.
AIMIM has won three seats and is leading in two seats, dashing the Congress's hopes of sweeping the election in the region.
Responding to the attack, AIMIM spokesperson Asim Waqar said, "Those calling us that have got a befitting reply and their mouths will now be shut in the future as well."
On whether his party was likely to go with the opposition alliance or the NDA, he said, "The decision will be taken by Asad (Owaisi) sahab, but the reality is that our fight is against the BJP and for the country. So the BJP and its alliance do not appear anywhere on our list."
The NDA is currently leading in 123 seats and the opposition alliance in 113 seats, in Bihar Election Results. The BJP is leading in 73 seats, the JDU in 45. The RJD is ahead in 74 seats, the Congress in 20 and the CPI-ML in 11 seats.
These projections are not as per the opposition alliance's expectations, especially after the exit polls predicted an easy win.
However, the Tejashwi Yadav-led alliance is giving a tough fight to the ruling coalition. With several rounds of counting remaining, the electoral contest is expected to go down to the wire.