Support for holding a plebiscite on same-sex marriage has plummeted with the majority of Australians now calling for a vote by politicians in parliament.

Forty-eight percent of Australians would prefer a vote in parliament while only 39 percent favour the Coalition's plans to hold a plebiscite, according to a Newspoll survey published today in The Australian .

Only 13 percent remain undecided on the plebiscite, which is expected to cost taxpayers $200m if it goes ahead.

Earlier this year polls showed 70 percent of the country supported the Coalition-backed plebiscite.

The Newspoll survey also revealed that if the plebiscite were to get pushed ahead on February 11 next year, 62 percent of voters would support a move for marriage equality.

Supporters attend a marriage equality rally in Sydney. (Source: AAP)

The drop in support for the “people’s vote”, which was first suggested by former Prime Minister Tony Abbott, coincides with a fall in voter confidence in the Coalition.

Earlier this week, PM Malcolm Turnbull said he believed the plebiscite was the fastest option for delivering a rounded decision on marriage equality. The Australian reports.

"We’ve set out a plan. I just say to Bill Shorten and the Labor Party and in fact to everyone that wants to see same-sex couples being able to marry, if Labor supports the plebiscite it will be held on the 11th of February. I believe it will be carried. I certainly will be voting yes."

Opposition leader Bill Shorten, who has lambasted the Coalition's plans for an expensive people's vote said the plebiscite was a financial black hole.