Hasina and Khaleda have alternated in power over the last 28 years. Elections in Bangladesh are often violent and marred by ballot-stuffing and voter intimidation.
Hasina's Awami League has held power since 2009 and dispensed from 2014 with a practice of letting a neutral caretaker government oversee elections, to the anger of the BNP.
The government has brushed off opposition fears of rigging.
"I don’t see any possibility this time, because all the parties are participating, and all of them will have their election agents,” said HT Imam, a political adviser to Hasina.
Bangladesh has seen steady economic growth under Hasina and the development of a vibrant garment sector under-pinning export growth, and accounting for 80 percent of the economy.
But rights groups have criticized increasing curbs on freedom of speech and the media.
Hope to capitalise on dissatisfaction, the BNP has formed an alliance with smaller parties called the National Unity Front and Hasina said this week she expected competitive polls.
The EU delegation in Dhaka said it was not sending observers because of growing demand for them amid tight resources.
India had no plan to send observers unless Bangladesh asked, an official at the Indian High Commission said.
