Earlier this month, local media reported the country's Deputy Health Minister as recommending gay marriage be legalised, during a speech reviewing marriage and family law.
Nguyen Viet Tien cited research on discrimination in saying gay people have the same rights as everyone else to love, be loved and marry.
The campaign manager for the pro-gay marriage group All Out, Hayley Conway, has told Radio Australia's Connect Asia that a vote at the moment would not attract a majority in the 500-delegate National Assembly.
"But with the Ministry of Justice and the Ministry of Health already coming out for marriage equality, we are fairly optimistic that by the time the vote is held in 2014, there could be the required number of delegates who would be in favour of an amendment," she said.
"The driving force behind this has actually been the recognition of human rights...and seeing the law as a violation of the human rights of same-sex couples and gay and lesbian people within Vietnam."
Homosexual relations are not illegal in Vietnam, but strong conservatism has led to discrimination.
Vietnam's Ministry of Justice began consulting on gay marriage last July.
It recently scrapped fines that had been imposed on same-sex couples who are caught getting married, after announcing just a few days earlier that those fines would be doubled.
Ms Conway says that points to some continuing uncertainty in the country.
"There is certainly between now and 2014, there is some work to be done with national assembly delegates to give them a very real idea of who these people are that the law effects," she said.
"They are in fact just people who are just like them who are looking to form families who have loving relationships, and changes to these laws are in line with human rights and with exactly what they're trying to do in terms of their human rights obligations internationally."
Vietnam held its first gay pride parade last August.