Mr. Turnbull voted yes, and urged other Australians to do so as a matter of fairness, seeking to blunt opposition from far-right members of his party.
Dean Smith, a federal senator from the right-leaning Liberal Party, who is gay, said that as a result of the survey, he would immediately introduce a bill to legalize same-sex marriage. He said on Tuesday that he believed he had the votes to pass the legislation in the Senate and send it to Parliament’s lower house for approval.
Lyle Shelton, a Christian lobbyist who was the “no” campaign’s most outspoken advocate, said he would begrudgingly “accept the democratic decision.”
“Millions of Australians will always believe the truth about marriage, that it’s between one man and one woman,” Mr. Shelton said. “It could take years, if not decades, to win that back.”
In 2015, Ireland was the first country to legalize same-sex marriage by referendum, but the same year, voters in Slovenia rejected a law legalizing such unions.
In the United States, Maine, Maryland and Washington became the first states to legalize same-sex marriage by referendum, in 2012; the country’s Supreme Court legalized same-sex marriage across the nation in 2015.
The survey in Australia was controversial, not only because it put such a thorny issue before the whims of direct democracy but also because of its cost.
The survey, a comprehensive — but expensive — opinion poll, was contentious from its conception. As the deadline approached for citizens to mail in their ballots, passions were inflamed by heartfelt pleas and vitriolic attacks.
Many advocates for same-sex marriage opposed the survey, saying that human rights should not be a matter for an up-or-down vote and urging Parliament decide the matter.
Estimates put the cost of the survey around 122 million Australian dollars, or $97 million. The poll was not a legally required step for changing the law.
The results on Wednesday results make the country’s path to same-sex marriage much clearer.
Mr. Greenwich said the outcome delivered “an unequivocal mandate for Parliament to legislate for this bill as soon as possible for a fair bill this year.”
Focus has already shifted to that bill, and what form it will take.
“After a cost of 122…