On Monday evening, the Australian Electoral Commission revealed almost 37,000 new voters had joined the electoral roll since the announcement of the same-sex marriage survey, with more than 434,000 others updating their details.

Those numbers are expected to climb in the next few days, with political parties, campaigners and publicly funded awareness campaigns encouraging people to register or update their details ahead of the Thursday deadline for survey enrolments.

According to AEC figures, there remain more than half a million people aged 18 to 39 who aren't on the electoral roll. But once people join the roll they are then required to vote in all future elections.

Over the last few days BuzzFeed News has spoken to MPs, strategists, and campaigners about how these new voters could affect the government's chances at the next election, tipped to be held next year.

One senior Liberal strategist said that while it remains unclear just how many of the tens of thousands of new voters are young or old — and how many have been energised politically by the "yes" and "no" campaigns — people are already making assumptions.

He said it's safe to assume they're more likely to be young and socially progressive.

"You're motivating a group of people, the large portion of them young, who are naturally going to vote against you at the next election," the strategist said.

"It's just not smart."