Bill Shorten has hit out at far-left and far-right Australia Day protesters, saying the national holiday shouldn't be an "idiot magnet".
The opposition leader zeroed in on people causing trouble at rallies, with tens of thousands expected to turn out at events around the country.
"It doesn't matter if you're on the far right or far left, Australia Day shouldn't be an idiot magnet," Mr Shorten told reporters in Melbourne on Friday.
While acknowledging the public holiday was a chance to celebrate, Mr Shorten also spoke of the hurt indigenous people felt on January 26.
"Today's a great day for all the new citizens, but it also is a day of great pain, in particular for all of our first Australians," he said.
Asked if he supported changing the Australian flag, Mr Shorten said making the nation a republic was higher on his to-do list.
"It's about making sure our first Australians are in the constitution and it's about saying we should have an Australian head of state. Those are my priorities."
Mr Shorten celebrated Australia Day by speaking at a citizenship ceremony in Melbourne's west, where he urged Australia to secure a fairer deal for indigenous and non-indigenous people alike.
"I think we owe our first Australians some imagination, some empathy, and some encouragement for their successes," he told the ceremony.
Mr Shorten, who opposes changing the date, said the debate had distracted from the task of building a more cohesive Australia.
"We need, instead, consider a voice in our parliament for our first Australians, and a meaningful say in the decisions which affect our lives."