US Vice-President Joe Biden has attacked "the gathering forces of racism" in America and Australia.
Mr Biden, who arrives in Australia on Saturday for a four-day visit, reminded both countries that they are nations of immigrants.
Donald Trump is set to take the Republican presidential nomination next week.
Pauline Hanson's One Nation is projected to win three seats in the Australian Senate.
And while Mr Biden didn't name either, it was clear who he had in mind when he told Fairfax Media: "When we encounter those who would exploit people's fears and divide us, we must remember who we are and all that unites us.
He said that "we must meet them as we always have—with courage and determination to move forward".
In his maiden visit to Australia, Mr Biden will seek cooperation with a major US cancer research initiative that he calls "a moonshot" to find cures.
He's expected to address domestic violence and to celebrate the military alliance with Australia.
The Vice-President told Fairfax Media that the US and its allies, including Australia, must "insist" that China observe the international rules-based system that governs claims to maritime territory.
"We expect China to play by the same rules as everyone else," he told Fairfax Media in written replies to questions.
An international tribunal in The Hague this week ruled against China's claim on South China Sea territory that is also claimed by the Philippines.
The Permanent Court of Arbitration said that under the UN Convention on the Law of the Sea, to which China is a signatory, Beijing had no legal claim.
China's government said that it rejected the jurisdiction of the tribunal and asserted "ancient rights" to the seas. The court has no enforcement mechanism, Mr Biden said that "we're urging both China and the Philippines to abide by the ruling".
The US works "with Australia, and countries throughout the region, to insist that the liberal international order be maintained as it relates to sustaining the free flow of commerce - keeping sea lanes open and the skies free for navigation".
The same court ruled against the US in 1986 in a case brought by Nicaragua.
The US has not signed the UN Convention on the Law of the Sea. Like China today, the US refused to abide by the court's decision.
The tribunal ruled that Washington pay Nicaragua an initial $US370 million for illegally mining the country's ports to bring down its socialist government. The US later settled the case. Mr Biden claimed that positions such as those of Mr Trump do not enjoy the support of most Americans.
"Let me be very clear, the xenophobic and hateful rhetoric that we are seeing splashed across the media does not reflect the history, the values, or the reality of the situation in the US. It is rejected by the vast majority of Americans today," he said.
He likened the US and Australia. "Our people share a foundational commitment to those democratic principles on which our nations are built - a commitment to advancing opportunity for all.
"The journey of America has always been that we overcome the voices of fear. And that's the story of Australia, too."
