Story highlights Australian PM's Labor Party voted her out of its leadership for former premier Kevin Rudd

Monica Attard: Julia Gillard was "a leader under siege" when she called for a leadership ballot

Gillard's strength of character was on display throughout her leadership, writes Attard

The first female premier placed sexism firmly on the agenda, says Attard

Australia has a new prime minister. And its first female premier, defeated in a decisive vote 57-45 in favor of the man she ousted in 2010, has now resigned.

With observers suggesting her government faces a landslide defeat in September's election, Prime Minister Julia Gillard was very much a leader under siege from within her own ranks when she called for a leadership ballot.

"I wouldn't be putting myself forward unless I had a degree of confidence about the support of my colleagues," she told Australia's Sky News in an exclusive interview ahead of Wednesday's ballot.

Gillard added that she would retire from politics if she lost the vote and the support of her parliamentary colleagues. She urged whoever challenged her to do the same. Gillard did not however name Kevin Rudd who promised to exit political life if he failed to win the support of his parliamentary colleagues.

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The change in the leadership of the Australian Labor Party comes a little over three years since Gillard toppled Kevin Rudd in a coup dubbed "the night of the long knives," and backed by key party power brokers. That was June 24, 2010.

Gillard went into a federal election in August 2010 with the Labor Party failing to win an outright majority in the parliament. She has since ruled with the support of three independents and a Green Party member.

But the political and public disquiet over the toppling of a sitting prime minister never abated. Hugely popular among Australians, Rudd, then foreign minister, challenged Gillard for the leadership in February 2012. He overwhelmingly lost the ballot and was relegated to the backbenches.

Gillard's strength of character has consistently been on display throughout her leadership. As leader, she is widely acknowledged to have deftly dealt with the challenges of a hung parliament. Her government has formulated and negotiated several critical pieces of legislation: a national disability insurance scheme and, on the day she lost power, a new formula to fund government schools.

Her feisty performance in parliament in October 2012, when she described opposition leader Tony Abbott as a misogynist, won her much admiration around the world. But among voters at home, she has experienced a steady decline in popularity.

In the past two weeks, polls showed her government would be overwhelmingly defeated in the election she had called for September 14. If the poll numbers hold through to the election, more than 30 Labor members of parliament will lose their seats.

The slings and arrows rarely stopped coming throughout her three-year tenure -- with much of the criticism becoming personal. Gillard has been criticized over her voice (described by many as nasal and monotone), the length of her nose, her fashion choices, and even her figure.

Whether Australians found it difficult to accept a female prime minister or not, her leadership placed sexism, particularly in public life, firmly on the agenda.

Gillard put the issue of misogyny back under the spotlight three weeks ago when she spoke to a new "Women for Gillard" support group and questioned if the opposition coalition would re-open the abortion issue in Australia if it won power in September. State, rather than federal, law governs abortion. Many Labor party backbenchers openly criticized Gillard for re-opening the issue, along with high profile feminists. It was viewed largely as a political stunt as was her reference in the same speech to the opposition coalition's "men in blue ties," who she said would banish women from political life. The speech saw a 7% decrease in support for her Labor Party in a poll subsequently released.

But the sexism issue also proved to be as damaging for political opponents -- particularly when the menu at a Liberal Party fundraiser recently was leaked to the media.

It described a main meal of quail with "small breasts, huge thighs and a big red box." Strongly condemned by opposition leader Tony Abbott, and despite denials that the menu was written as a joke by the owner of the restaurant where the fundraiser was to be held and was not endorsed by the Liberal Party, "Menu-gate" as it became known, added credence to Gillard's argument.

In the same week, while in Western Australia to discuss her reforms to education funding, Gillard was asked by a radio shock jock whether her partner, Tim Mathieson, a former hairdresser, was homosexual. The implication of the question was that her relationship was a sham given Gillard's refusal to marry, which has played poorly among some voters.

"Well, that's absurd," responded Gillard.

Howard Sattler who was later sacked.

A few days later, another radio announcer criticized Gillard for showing too much cleavage.

"I don't think it's appropriate for a prime minister to be showing her cleavage in parliament... I just think it is inappropriate. I don't want to see any politician's flesh in parliament," Grace Collier told an ABC Radio program.

Following these comments, Gillard's army of female supporters took to posting photographs of their breasts on Twitter using the hashtag "convoyofcleavage."

But over the past two weeks, Gillard's staunchest parliamentary and ministerial supporters have declared their continued support for her. As her popularity among voters waned, Rudd took to the streets where reaction to his every appearance was of a rock star proportion.

Rudd consistently denied he would challenge Gillard for the leadership. He was a "no show" in March this year when Gillard reacted to leadership chatter by calling a ballot that was not contested. But on Wednesday, as his supporters gathered signatures to a petition calling for another ballot, he changed his mind.

He said Australians wanted a real choice.

"At present, they don't feel as if they have got one," Rudd told a news conference ahead of the ballot. "They are frustrated and angry that we are leaving them with little choice other than to vote for Mr Abbott."

Widely credited with having steered Australia through the global financial crisis, Rudd told the conference Australia needed his steady economic leadership because the country's resources boom was ending.

"Given our economic relationship with China accounts for 10% of our economy this is a massive challenge," Rudd said. "Diversification is essential for Australia if we are to protect our jobs and maintain our living standards."

Rudd also promised he would not seek retribution against any of his parliamentary colleagues who, since the last leadership ballot he lost in March 2012 have paraded their disdain for him. He said he would embrace those wanted to continue working with him and would thank those who refused, for their services.

The decision to change leader may now trigger a constitutional crisis if the country's Governor General demands proof that the Mandarin speaking Kevin Rudd can harness the support of the parliament.