Ratification of the Trans-Pacific Partnership in the United States was never expected to be easy.
The shock decision by Hillary Clinton, the Democratic Party front-runner, to oppose it gives an early indication of just how fraught the process is likely to be.
That looks like bad news for the Vietnam which will need to reassure sceptics in Congress that it is a worthy partner of the US.
Vietnam’s inclusion in the TPP would be seen as a triumph for the Vietnamese government, even though it carries risks for the Communist Party and could give a rare boost to reformers and activists campaigning for change in the country.
The potential economic benefits for Vietnam of the TPP are so overwhelming that even conservatives in the leadership have had to swallow their misgivings and support it.
But they remain extremely wary about provisions that seek to guarantee workers’ rights, including the freedom to organise independent unions, and pressure to open up the economy to further privatisation and foreign investment.
Analysts caution against expectations of any immediate radical change. The communist leadership in Hanoi will attempt to minimise any reforms, and to resist provisions that seem to challenge its monopoly on power.
But the pressure on Vietnam could increase as the US begins the long and tortuous process of ratification.
Critics in Congress will point to its authoritarian communist government, its record on human rights and religious freedom, and its poor labour practices and restrictions on workers’ rights.
Labour is the battleground where Vietnam could be most vulnerable to pressure. It is seen by some activists and campaigners as the key to broader gains in political freedom and respect for human rights.
The TPP requires member countries to accept key labour rights as outlined in the 1998 declaration of the UN’s International Labour Organisation (ILO).
They include allowing workers the right to free association and collective bargaining, the right to a minimum wage and safe working conditions, and an end to forced labour and child labour.
Any violations could be subject to trade penalties under the terms of the TPP.
But before that stage is reached, Vietnam will have to convince its critics in Congress that it is willing to drop restrictions on the formation of free trade unions.
The Communist Party currently controls the labour union system and has not tolerated any challenge to its monopoly on power.
Some activists in Vietnam say they have little hope of real change, at least in the early stages. They expect the authorities to work through proxies and affiliated organisations to give an impression of change – without making fundamental concessions.
But Vietnam will come under more intense scrutiny and will have to accept the close monitoring of its labour practices for many years by an independent commission of experts.
Abuses have also been highlighted in areas such as child labour, sex discrimination, the treatment of pregnant women in the workforce, low wages and long working hours.
Vietnam will be subject to challenge in all these areas by any of the member countries of the TPP. Activists working inside Vietnam can expect much more leverage as they seek to press reform upon the government.
Congress in the United States is scheduled to take a vote within 90 days of President Obama signing the TPP.
The process, however, is likely to take much longer and Vietnam will be extremely uncomfortable with the prolonged period of scrutiny that can be expected.
Any concessions by Hanoi will be further complicated by political infighting in the run up to the leadership changes expected at the Communist Party Congress due early next year.
There does appear, however, to be consensus in Hanoi on the need for the TPP.
The party depends to a large degree on economic growth to maintain its legitimacy, and the TPP promises an extraordinary opportunity for growth – with enhanced access to the vast markets of Japan and the United States, and an expected surge in investment by foreign manufacturers.
Closer economic and regional ties with Washington also have the benefit of putting China on notice that it can no longer take its economic and strategic position in Vietnam for granted.
Inclusion in the TPP could be a decisive moment for the Vietnamese Communist party – but observers caution that many battles remain to be fought before real change can be expected.