The peaceful march on Sunday, December 29, headed by opposition leader Sam Rainsy and his deputy Kem Sokha, was the largest of its kind in over a decade. Phnom Penh's streets rang with calls for Hun Sen to quit, something that would have been unthinkable even a year ago.
The movement to unseat Hun Sen, who has been at the helm of one of the world's most corrupt nations for nearly three decades, is being led by the opposition Cambodia National Rescue Party (CNRP).
The CNRP came close to winning July's general election. It claims widespread cheating by the ruling party cost it victory.
The official election results handed the CNRP 55 seats in the 123-seat National Assembly, with the rest going to the ruling Cambodian People's Party (CPP). However the opposition's MPs-elect have refused to take their seats, and the party wants fresh elections to be held in 2014.
Before the march began, Rainsy told his supporters gathered in the capital's Freedom Park that Hun Sen's government was illegal.
"Hun Sen will hear our demands, and he cannot do anything against the will of the Cambodian people," Rainsy told the cheering crowd. "Today we all want to see a change in the leadership of the country. So please resign!"
That seems unlikely. Hun Sen last week rejected that demand, as he has the opposition's calls for a new election and for an independent probe into credible allegations of widespread election fraud. (The lack of an impartial investigation means it is unclear how much difference the chicanery at the polls made to the final result.)
Wage increase insufficient
Rainsy's campaign has been helped by the support of tens of thousands of garment workers, who are traditional supporters of the CNRP, and whose loyalty was further boosted after the opposition pledged to double the minimum wage if it won the election.
So it was hardly a surprise that garment workers walked out last week after the government announced that the monthly minimum wage for the sector's 400,000 workers would rise just 15 US dollars - from 80 to 95 dollars.
The garment sector, worth 5bn US dollars this year, is Cambodia's largest formal employer and its biggest foreign exchange earner. It is staffed mainly by young women who are expected to support their siblings and parents in rural areas.
But their low wages mean they are compelled to work overtime simply to make ends meet. Real wages have declined over the past decade, and rising prices for basics in the markets mean many are now struggling.
That is the experience of sewing machine operator Touch, 35, who attended Sunday's rally. She works at a factory in Phnom Penh that makes jeans for US brand Levi Strauss. Touch and her husband cannot afford to have their two children living with them in the capital, so the youngsters stay with extended family in her home village in Takeo Province.
Between them, the couple sends home small sums each month, but inflation means that has become much harder. The workers had expected a far bigger raise, she explained.
"And so there are two reasons I came today," said Touch, who has worked in the sector for a decade. "One is to have the minimum wage increased to 160 dollars. And the other is for Hun Sen to step down."
Touch and her colleagues - Sarith and Saran, each of whom has a child living with their respective parents in the provinces - expect that some sort of deal will be struck between the government and the unions that led the walkout.
Labor ministry representatives met with unions on Monday to discuss the minimum wage demands, but that meeting closed without success.
"We don't know how long that process will take," said Touch of the effort to boost the minimum wage. "But until a deal is done, we won't return to work."
Until then, Cambodia's garment industry remains closed. The Garment Manufacturers' Association in Cambodia (GMAC), the trade body that represents the 470-odd factories making and exporting garments on behalf of foreign buyers, took out full-page adverts in the press Monday, December 30, saying it was "unable to continue operations given the current situation."
GMAC blamed six unions - all independent or affiliated with the opposition - for the problems and accused them of threatening workers and destroying factory property. GMAC also criticized the Ministry of Labor of failing to rein in the unions.
"We would like these trade unions and the [ministry] to guarantee the safety of our workers who want to work, to guarantee and safeguard all our property," GMAC stated, adding that it would not resume talks with government and unions until that happened.
Pro-CPP unions have also pledged to lead protests of their own this week, saying some garment workers did not support the strike action that had shuttered their factories.
"The workers who did not join in the protest are angry because they are not earning a salary, so they will protest against the CNRP and [other] unions," Chuon Momthol, the president of the Cambodian Union Federation, told the Phnom Penh Post newspaper. "When the investors or factory owners walk away, the opposition party officials won't starve, but the workers will."
Ou Virak, the president of the Cambodian Center for Human Rights, an NGO, said that those marching on Sunday represented an "encouraging" cross-section of Cambodian society. Other than garment workers, there were Buddhist monks, young people and old, urban residents and villagers who had come to the capital.
Many Cambodians have become openly critical of a government that is corrupt, complicit in land-grabbing, favors the rich and powerful at nearly every turn, and whose service provision in areas such as health and education remains poor.
"And I think that's a good sign," said Virak. "It is unprecedented, and it could hopefully strengthen accountability for politicians."
He said the groundswell of support for change among ordinary people provided a powerful mandate for the opposition.
"This is a time for leadership, and I think the opposition needs to step up its game a bit and provide mature leadership with real vision - and that could definitely make the opposition even stronger," he said.
Over the weekend, the CNRP announced that it would suspend all marches until January 5 in order to give the CPP time to respond to its offer to restart talks.
Getting back around the negotiating table is key, said Virak, but the opposition would be wise to keep its protests going to ensure that it approaches talks from a position of strength.
"At the same time, when leadership is needed, I think the opposition needs to be more reasonable in their demands," said Virak, explaining that Rainsy's call for workers to stay on strike until the minimum wage was increased to 160 dollars, for instance, could spook investors.
Turning to the ruling party, Virak said that the prime minister would "need to understand that his popularity is not as high as he used to think it was."
"Hun Sen needs to start looking at his legacy, which means he needs to start looking for a way out and looking for a legacy of his own," he said. "And if that is the case, maybe the ruling party will find some room to put in place real reforms - and maybe it will also not stay as a bunch of old men, but will bring in some younger, more energetic and more creative minds and move the [CPP] forward."