The protesting Awami League and its supporters said they will boycott the Jan. 22 election.
"We will not accept farcical elections. We will shut down the country for weeks if the government goes ahead with holding the elections," opposition spokesman Abdul Jalil told the BBC.
But Ahmed, head of an interim government that assumed control in October, said the constitution requires the election be held within 90 days.
Protesters want the election delayed. At issue is what voter registry the government uses.