Opposition Leader Bill Shorten kicked off Kristina Keneally's by-election campaign for the Sydney seat of Bennelong, telling members Labor has 27 days to win over 9000 voters.
Hundreds of Labor stalwarts wearing red t-shirts and holding balloons and signs endorsing Ms Keneally packed out the Civic Hall in Ryde in Sydney's northwest.
Ms Keneally, the former NSW premier, has been parachuted in to stand against former Liberal MP John Alexander, following his resignation over his citizenship status.
A Galaxy Research poll published on Saturday showed the Bennelong by-election will be a tight race, with Labor boasting a 10 per cent swing on a primary vote basis, up to 39 per cent against the Liberal Party's 42 per cent.
"We need you to persuade people to give their first vote to Kristina Keneally," Mr Shorten told the gathering.
He was quick to criticise the government's front bench for lashing out at Ms Keneally after announcing her candidacy.
"As soon as Labor announces a strong woman to run for parliament, that mob of angry elitist, out-of-touch conservatives on the front bench immediately went nasty," he said, to shouts of "shame".
"They are so out of touch about the role of women in modern Australia."
Ms Keneally was given a standing ovation and received hugs from state and federal members of parliament as she took to the stage, receiving rounds of applause as she talked about Medicare and access for all children to quality education.
"My life was transformed by education - my mother was the first in my family to go to university."
She vowed to campaign hard on both issues for the constituents of Bennelong.
