A new poll shows support for marriage equality in Australia has weakened.

The news comes as Australians vote on whether the government should extend marriage rights to gay and lesbian couples. The government is asking all of Australia's more than 16 million voters to weigh in on the issue through a postal vote at an estimated $120 million cost. Results are expected on November 15.

The Australian newspaper over the weekend published results of a poll conducted by Sydney-based market researcher Galaxy Research which showed that support for same-sex marriage had fallen from 62 percent five weeks ago to 57 percent, and opposition had grown 4 points to 34 percent. Nine percent of respondents did not answer.

Results of the postal survey are non-binding.

Opposition leader Bill Shorten said that he still expects the “yes” vote will succeed and reiterated his opinion that the survey is an “amazing waste of money.”

“We all know the survey is an amazing waste of money,” he told Sky News. “The fact that we've got a Newspoll survey telling us that we're going to spend $120 million to find out really highlights the futility of it.”

Green Senator Sarah Hanson blamed the dip in support on the “no” side's “relentless negative campaign.”

“When you are trotting out people like Tony Abbott, who is basically blaming marriage equality for everything unsavory, for all the terrible things [that] are going to happen. It's inevitable that that side of the campaign is going to be given more attention,” she said.