The Vietnam of today wasn't what Le Hieu Dang had hoped for when he joined the Communist Party 40 years ago to liberate and rebuild a country reeling from decades of war and French and US occupation.
The socialist system of the late revolutionary Ho Chi Minh has been corrupted, he says, by a shift to a market economy tightly controlled by one political party that has given rise to a culture of graft and vested interests.
"I fought in the war for a better society, a fair life for people. But after the war, the country has worsened, the workers are poor, the farmers have lost their land," Dang said
"It's unacceptable. We have a political monopoly and a dictatorship running this country."
In Vietnam, where free speech is stifled and the image of unity in the Communist Party of Vietnam sacrosanct, analysts say the significance of comrades speaking out publicly cannot be understated.
The party-dominated National Assembly on Thursday approved amendments to a 1992 constitution that, despite a public consultation campaign, entrench the party's grip on power at a time when discontent simmers over its handling of land disputes, corruption and an economy suffocated by toxic debt amassed by state-run firms.
Dang is vehemently against the amendments and not alone in his views. They are of the kind that have landed dozens of people in jail as part of a crackdown that's intensified as dissent has risen and the number of internet users has soared to a third of the 90 million population.
What has jolted the party is that the loudest calls for a more pluralist system are coming not from the public, but from within its ranks, an open act of mutiny not seen since it took power in a reunified nation in 1975.
"Vietnam has entered a new phase. The existence of rivalries within the party is already known, but it's now more transparent in a way never seen in the past," said Jonathan London, a Vietnam expert at City University in Hong Kong.
"The rise of this group and its advice will influence the tenor of party discussion. What's clear is this is a period of uncertainty and competition."
This year, Dang and 71 others, among them intellectuals, bloggers and current and former party apparatchiks, drafted their own version of the constitution, in response to a routine public feedback campaign.
Their draft was posted online and 15,000 people signed an accompanying petition that called for the scrapping of Article 4, which enshrines the party's political monopoly.
But lawmakers did just the opposite and redrafted the article to expand the party's leadership role and the military's duty to protect it.
"Theoretically, democracy is not synonymous with pluralism," the commission said in a report in May. "No one can affirm that multiple political parties are better than one party."
On Thursday, not a single lawmaker rejected the new draft.
A draft of the amendments, which was published weeks ago, outraged opponents.
The initial 72 democracy advocates were joined by others and 165 of them, including some retired government officials, published a statement on the internet two weeks ago warning lawmakers to reject the amendments.
They said if National Assembly members passed the amendments, they would be complicit in a "crime against the country and its people.".
Dang and his allies plan to remain in the Communist Party so that they can drum up support from the disenchanted members to set up an opposition party to scrutinise the ruling policies and try to keep it in check.
Despite their fierce rhetoric, they insist the plan to set up the Social Democratic Party is not an attempt to overthrow the ruling party but an attempt to create a more liberal coexistence between parties that would benefit the country.
Ho Ngoc Nhuan, vice-chairman of the Ho Chi Minh City branch of the Fatherland Front, the party's umbrella group that manages big organisations under Marxist-Leninist principles, said the party was out of touch with the people.
It was time, he said, to shake up Vietnamese politics.
"We face many problems in Vietnam, big crises, so how can we solve it with one all-powerful party? We have to get their attention, so we're calling comrades in the party to join us so we can break this chain," Nhuan said.