Key opposition leaders will address the protesters
An alliance of opposition parties in Nepal has called for the biggest display of anti-monarchy protests in the capital, Kathmandu, on Tuesday, setting up a showdown with King Gyanendra.
Rallies are to be held along the ring road, which encircles the capital, in a vast show of strength.
For the first time, opposition leaders - who have been conspicuous by their absence - will make an appearance.
Leading politicians, including former premiers Girija Prasad Koirala and Sher Bahadur Deuba and communist leader Madhav Kumar Nepal, will address the protesters at key intersections.
After nearly three weeks of protest, many believe the time is ripe for the political leaders to take charge and direct the challenge to the monarchy.
The protests, which have been gaining in strength in the past few days, have patently lacked leadership.
Observers say that if they do not step in now, the protests risk losing focus and may peter out.
"It needs someone like a Girija Prasad Koirala to make an appearance and energise the crowd," said one Kathmandu-based diplomat. "They need a visible figure to rally around."
There is another reason why the opposition has chosen to step in at this point.
Protests across the country have continued for nearly three weeks
There are very real fears that Maoist rebels could well use the opportunity to fill the void and take control of the protests.
Maoist activists are already believed to have been present at many of the rallies, and there have been several instances of Maoist campaign pamphlets being distributed among the protesters.
The last thing the parties want is for the protests to spin out of control and for the Maoists to move in, a view that is fast gaining currency.
The opposition parties and the Maoists struck a deal last year to take on the king, a move that was criticised by some.
On Monday, Maoist rebels launched an attack in north-eastern Nepal in which several people were killed.
The government was quick to point out that the attack was more evidence that the rebels continue to pose a major threat and have not given up violence.
It is a view that is not lost on the political parties, who are aware that they have to contain the influence of the Maoists to prevent a possible takeover by the rebels, something that many international governments, including the United States, have openly warned could happen if the present crisis is not resolved.
Analysts say King Gyanendra may believe he can stand firm
The parties have said that they would be satisfied if the king reinstates the country's parliament, which could then call for elections to a constituent assembly.
That would pave the way for a redrafting of the constitution and, almost certainly, a rethink on the position of the monarchy.
But there are some who believe that the king still thinks he can hold out and hope that the protests lose their intensity.
Many of the protesters have travelled from the countryside and will eventually have to head back home to their villages to tend to their farms.
It is a strategy that is fraught with risk and could well lead to a collapse of the monarchy, say analysts.