Commissioner M.A. Aziz has brushed off calls to quit despite calls from the interim government and the opposition, which has threatened more mass protests if its demands are not met by Friday.
Aziz is accused of overseeing the compiling of an electoral list containing more than 10 million fake voters, tilting polls due in January heavily in favour of the outgoing government.
The clock is ticking for the interim administration, and not only to the opposition's extended deadline.
The body has 90 days from last Sunday to organise elections before its term expires but under Bangladesh's constitution, sacking Aziz would be a lengthy process.
"If he does not step down on his own ... the caretaker government will have to think of how the commissioner can continue without it affecting the holding of free and fair elections," a member of the 10-person advisory council, or cabinet, told AFP.
The main opposition Awami League wants Aziz and his two deputies sacked alleging that they have tried to rig the polls by drawing up a voters' list that includes phony voters and leaves out many of its own supporters.
It says that unless the supposedly neutral caretaker body removes the officials, the elections will be weighted towards the Bangladesh Nationalist Party whose five-year mandate expired last Friday.
At least 25 people died and more than 2,000 were injured in four days of bloodshed after that day, with pitched battles between police, opposition supporters and rival party activists across the country.
In addition to sacking Aziz and his two deputies, the opposition has a string of other demands ranging from removing portraits of the outgoing prime minister, Khaleda Zia, from government offices to purging the civil service of biased officials.
The interim body removed a number of senior officials last week in a bid to convince the opposition of its neutrality.
Top-ranking officials seen as loyal to the BNP were sacked including the national police chief, and a crackdown to weed out biased civil servants in sensitive posts was also launched.
Political bickering and inefficient government have characterised Bangladesh's 35-year history and are largely blamed for the impoverished South Asian country's failure to benefit from its considerable natural resources.

Copyright AFP (Agence France-Presse), 2006