he country's rival parties disagree over some key issues and are widely expected to miss the deadline, further aggravating public disillusionment with the political process.
Analysts say the prolonged deadlock raises the risk of unrest in the impoverished Himalayan nation, where lawmakers this week threw chairs and scuffled with each other as tempers frayed.
An estimated 1,000 police have been deployed around the parliament building after the violence this week spilled over onto the streets.
"We have waited so many years, we are tired of these leaders," said Kathmandu-based trader Mr Niraj Shrestha, reflecting a growing sense of frustration with the political process.
"If our lawmakers want to, they can draft the constitution in 24 hours, but I don't think even another 24 years will make a difference to their way of functioning," the 39-year-old told AFP.
The constitution was intended to conclude a peace process begun in 2006 when Maoist guerrillas entered politics, ending a decade-long insurgency that left an estimated 16,000 people dead.
Six prime ministers and two elections later, discord between the opposition Maoists and ruling parties has intensified, paralysing the drafting process.
A key sticking point concerns internal borders, with the opposition pushing for provinces to be created along lines that could favour historically marginalised communities.
Other parties have attacked this model, calling it too divisive and a threat to national unity.
The ruling parties and their allies have the two-thirds parliamentary majority they need to approve a constitution without Maoist support.
But the former insurgents have warned them of further conflict if they fail to take opposition views into account.
Maoist spokesman Dinanath Sharma told AFP that ruling coalition leaders had refused to meet with the opposition.
A missed deadline will prolong instability in a country where one out of four people survive on less than $1.25 a day, according to World Bank data.
Lawmakers from the ruling Nepali Congress told AFP they intended to push on with a proposal for a vote on January 22.
"How else can we move forward? The current environment is not positive to hold talks," Information Minister Mr Minendra Rijal said.
But analysts say such measures would alienate marginalised communities and spell disaster for the country.
"A constitution achieved with only minimum consensus will have no scope of success," said Mr Lok Raj Baral, executive chairman of the Nepal Centre for Contemporary Studies.
As the deadline approached, senior Maoist leader Mr Narayan Kaji Shrestha told AFP he saw almost no chance of an immediate agreement.
"We were hoping to at least complete a draft constitution but even that hasn't happened," Mr Shrestha said.
"We cannot wait three more years, the people won't forgive us."
by Paavan MATHEMA
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