Gay marriage has won the unconditional backing of U.S. President Barack Obama last week and Argentine President Cristina Kirchner is sending an appeal letter to Prime Minister Julia Gillard, all representing the series of events that marriage equality advocates hope would prompt the Australian government to rethink its position on the controversial issue.

Ms Gillard, however, appears unchanged by the seeming growing support that same-sex marriage has been collecting lately, declaring in a radio interview with ABC that "'I believe what I believe ... and my view's not changing."

And with her counterpart in the Coalition, Opposition Leader Tony Abbott, even more taking a hardline stance on the matter, the prospect of Australia accepting gay unions anytime soon seemed far off for now despite the earlier submission of three different bills pushing for gay marriage before the Parliament.

Greens Senator Sarah Hanson-Young, whose direct appeal before the local authorities in the Argentinean capital of Buenos Aires led to the wedding of an Australian couple in the South American nation recently, has earlier called on Ms Gillard to follow the lead of Mr Obama.

Her Greens colleague, Melbourne MP Adam Bandt said on Saturday that the landmark revelation last week from the U.S. president reflected the unfolding reality that nations around the world have started embracing gay marriage.

"If it's good enough for the leader of the free world, it should be good enough for the leaders of the political parties in Australia," Mr Bandt, who authored one of the standing same-sex union bills, was reported by the Australian Associated Press (AAP) as saying.

He addressed the thousands of crowd that convened over the weekend in a number of key Australian cities that showed support for the legalisation of gay marriage in the country.

According to AAP, politicians and celebrities lent their names to the weekend campaigns that organisers hoped would prod federal authorities to open up on the creeping reality of gay marriage.

As peaceful protesters poured into major Australian streets, a group called Doctors for the Family made public its Senate submission, which highlighted its claim that marriage between a man and a woman forms the "basis for a healthy society."

Lachlan Dunjey, convener for the group that reportedly brings together about 150 medical doctors, told ABC that Australia needs to stick with the present definition of marriage under the Marriage Act of 2004.

His group, Mr Dunjey added, also expressed grave concerns on the well-being of children that would be raised by gay couples, whose relationship, he stressed, may not prove as stable as those of conventional couples.

"It's well proven that children who grow up with a mother and a father in a biological mother-and-father family do better than children who don't have the opportunity to grow up in that kind of family," Mr Dunjey said.

But the group's submission was shot down today by the Australian Medical Association (AMA), which countered that the claims being peddled by Mr Dunjey stood on questionable medical arguments.

"There is a growing body of evidence that says there's no difference in their psychological development, their general health, their sexual orientation," AMA president Steve Hambleton told ABC on Monday in explaining that homosexual and heterosexual couples can equally raise healthy children.

"It's certainly not the opinion of the AMA body of doctors," Mr Hambleton added as he flatly rejected the group's submission.

The AMA chief stressed too that the public must be aware of the fact that majority of Australian doctors, which now number to about 90,000 as per AMA count, hold the belief that any parents, regardless of their sexuality, must enjoy the right and opportunity of having a normal family environment.