Australian Marriage Equality (AME) said they feel 'deeply embarrassed' that they are falling so far behind their neighbor is passing same-sex marriage law.
New Zealand are set to legalize gay marriage today, whereas neither Australia's prime minister Julia Gillard nor opposition leader Tony Abbott supports marriage equality.
A same-sex marriage was overwhelmingly rejected by the House of Representatives and the Senate in Australia last September.
AME blamed Australia's political leaders for failing to support gay marriage and said the effect of New Zealand passing legislation first will mean that 'the world's attention will be on New Zealand's achievement, and Australia's corresponding failure'.
The Australian campaign group also ran a survey to see how many Australian same-sex couples were planning to go to New Zealand to marry and found that 1,000 couples said they would.
'Australia will lose a proportion of the estimated $700 million same-sex couples plan to spend on their weddings, as these couples spend their money in New Zealand instead,' said a statement from AME.
AME added that the New Zealand vote puts pressure on the Australian state of Tasmania to pass same-sex marriage law.
The state's Upper House, who voted down a marriage equality bill last year, are voting on the matter again on 4 May.
'The majority of Australians who support marriage equality do not want us to fall behind New Zealand, but with the federal parliament unwilling to tackle this reform it is up to Tasmania to take the initiative,' said AME spokesperson Rodney Croome.
'Hundreds of couples will travel to New Zealand to marry and spend money that would have been spent in Tasmania if reform had been passed last year.'