“So there’s only one thing left to do,” Mr. Wilson said, his voice choking. He turned to the public gallery, where Mr. Bolger was sitting. “Ryan Patrick Bolger, will you marry me?”

The answer from Mr. Bolger, who broke into a smile, came loud and clear. As the chamber applauded, the deputy speaker, Rob Mitchell, made sure it would go down in history.

“I should let Hansard note to record that that was a ‘yes’ — a resounding yes,” Mr. Mitchell said, referring to parliament’s official record of transcripts. “Congratulations.”

Full passage of the same-sex marriage bill, which has drawn widespread, cross-party support, would make history in Australia. The bill easily passed the Senate last Wednesday without amendment following a debate on whether it included enough religious freedom provisions. The bill gained momentum earlier this month after Australians voted decisively in a nonbinding referendum in favor of making same-sex marriage legal.