In the last election in 2004, the BN won nearly 64 per cent of the popular vote and more than 90 per cent of the seats in all-important lower house of parliament.
But analysts say this time there may be no easy victory and a sharply reduced majority could threaten Abdullah Badawi's position as prime minister, leading to a shake-up of the coalition, its cabinet line-up and policy platform.
The opposition says the BN is running scared and the country's Election Commission this week scrapped plans to use indelible ink to prevent vote fraud, citing legal and security fears.
The commission had widely advertised the planned use of the special ink – applied to a voter's fingernail after casting their ballot – as its response to long-standing allegations of vote-rigging.
But the decision to scrap the plan it drew a warning from the electoral reform group Berish that "phantom" voting would be made easier and that these would be the "dirtiest elections ever".
Last November Bersih - a loosely aligned group of civil society organisations and political parties - led thousands of people on to the streets of Malaysia's largest city, Kuala Lumpur, in demonstration demanding electoral reforms.
That protest was put down by riot police with tear gas and chemical-laced water cannon.
Another rally two weeks later by thousands of ethnic Indians protesting against discrimination drew a similar police response.
Race and faith
The issues of race and faith also were becoming much more sensitive, commentator Karim Raslan explained to Al Jazeera.
"These now are becoming issues that non-Malays want to have their rights defended and prosecuted at all costs," he says.
"The situation where non-Malays were willing to live with whatever they've got has gone."
|A total of 222 parliamentary and 505 state |
seats are up for grabs on Saturday [Reuters]
Last year the country's top civil court rejected an appeal by Lina Joy, an ethnic Malay woman's, to be recognised as a Christian, ruling that she must go to the Islamic court – where she could face prosecution – to formally recognise her conversion.
The Lina Joy case highlighted a string of others - with accusations of bodies taken from families for religious burials and children taken from converts – and sparked charges of religious persecution.
In a country where politics and power are organised along racial and religious lines, minority ethnic Indians and Chinese, who together make up about a third of the population, have been turning up in droves to night-time opposition rallies in the past two weeks of campaigning.
The two communities have shown clear signs of discontent with the coalition, which is dominated by the United Malays National Organisation - the biggest ethic Malay party - and the BN concedes that a protest vote by Chinese and Indians could cost them some seats.
But the coalition says it needs to retain a two-thirds majority in parliament to ensure stability in the country.
The last time it failed to win a two-thirds majority, in 1969, race riots broke out and a state of emergency was declared until 1971.