Slowly but surely, Liberal senator Dean Smith’s quivering lip steadied, then a quick flash of teeth – a grin – told the story.

“I never believed the day would come when my relationship would be judged by my country to be as meaningful and valued as any other,” the gay, conservative politician told Parliament.

“The Australian people have proven me wrong.”

In a historic moment, Senator Smith kicked off debate on his same-sex marriage bill on Thursday, one day after more than 60 per cent of Australian voters backed the social reform.

Senator Smith’s deeply personal speech was the start of a cathartic morning in the Senate, setting in motion a retelling of the personal trials and national tribulations on the road to reform.

Opposition Senate leader Penny Wong, who has two children with her partner Sophie, told of her horror at Labor’s support for the Howard government’s amendment to the Marriage Act in 2004.

“I had a choice at that time,” she said. “I could go out in a blaze of publicity, take a public stand against my party and become an outsider in a pretty dramatic way.”

Labor’s Penny Wong has been a strong advocate for same-sex marriage. Photo: AAP

Instead, she chose to “fight this discrimination from within the political system”.

“This is the most personal of debates because it is about the people who matter most to us,” Senator Wong said.

“It is about the people we love.”

Draped in a coloured scarf, Greens Senator Janet Rice told how for the first half of her marriage, “we fitted the stereotype of a perfect couple with a perfect family”.

“But 17 years after we first married, Penny transitioned, affirming her identity as a woman,” Senator Rice said.

“And I still loved her. I affirmed my sexuality as bisexual. We went from being the perfect family in the eyes of others to being weird.”

Greens Senator Janet Rice is in a same-sex relationship. Photo: AAP

At first, public displays of affection were swapped for self-censorship, Senator Rice told the Senate.

“But we know our relationship hasn’t changed, our love is still the same as it was 31 years ago,” she said.

“And our two sons have been wonderful, well-adjusted, young men. They are living proof that the hatred and attacks on same-sex couples and the wellbeing of our children are groundless.”

For Senator Rice’s partner, Penny, a change in the marriage laws will allow her to affirm her gender on her birth certificate, without the couple needing to divorce.

Dean Smith was met with hugs and a standing ovation. Photo: AAP

As the Parliament prepares to mull amendments to Senator Smith’s bill, another same-sex attracted senator, Labor’s Louise Pratt, offered a warning.

“Australians voted for equality, not for more discrimination,” she said.

“To legislate to give people a right to discriminate on the provision of goods and services would simply go too far.”

Liberal Cabinet minister Simon Birmingham was the first straight senator to address the Senate.

Senator Birmingham, the Education Minister, was one of the first Liberal politicians to back the reform as a junior politician in 2010.

He noted Senator Smith’s entry to the Parliament, and his conversion to the same-sex marriage cause in 2015.

“That was a turning point in the debate within the Liberal Party. For we had a champion that wasn’t just someone like me, arguing from a position of believing it was right, but someone for whom it directly impacted on their life,” he said.

“And in Dean’s arguments that he put, it of course meant that anybody who looked Dean in the eye, and argued against him, was arguing that he did deserve the right of marriage equality.”

More than 20 senators were listed to speak on the bill on Thursday.

The debate will continue on Friday.