Voters in the US are not convinced the Indo-Pacific should be a priority region for the Biden administration, and isolationist sentiment in the country continues to rise, according to a new analysis by the United States Studies Centre.

The new USSC State of the United States report, to be launched in Canberra at an event on Wednesday with the defence minister, Peter Dutton, Labor frontbenchers Penny Wong and Brendan O’Connor, and US congressman Joe Courtney, finds support for the US alliance with Canberra remains strong.

But the USSC’s chief executive, Prof Simon Jackman, says the US in 2022 is “consumed by a fractious debate about its role in the world, and is almost paralysed by disunity”. The new analysis draws on YouGov polling undertaken in the US and Australia last December. The US sample size was 1,200 and the Australian sample size was 1,211.

The data shows isolationist beliefs in the US have increased steadily from 28% of respondents in 2019 to 40% at the end of 2021. The new report also notes that prior to 2016, the American National Election Studies – a time series dating back to 1952 – has never found more than 30% of Americans holding isolationist beliefs.

While Joe Biden has stressed the importance of nurturing alliances since winning the White House, voters in the US appear more ambivalent. The largest group of respondents – around half or more – felt alliances made the US neither more nor less secure. This suggests, the report says, “the majority of Americans are unsure about the value of US alliances”.

As well as growing isolationism, there is also pervasive pessimism. Voters in both the US and Australia also believe America’s best days are behind them (60% of respondents in the US and 70% in Australia).

The research suggests people who voted for Biden in 2020 “are now just as pessimistic about the future of the United States as they were during the Trump administration, while the Republicans’ preferred candidate for the 2024 presidential election remains Donald Trump”.

Jackman says the analysis suggests the US currently lacks the national unity that leaders of Australia’s defence and diplomatic establishment view as the critical ingredients of our national defence.

“The implication for Australia is clear,” Jackman said. “While the US alliance remains Australia’s single most valuable strategic asset, Australia must continue to rapidly evolve its own capabilities, resilience and autonomy.”

Jackman said realising the potential of the Aukus partnership would “require unrelenting focus and attention in Washington, cutting through domestic political division, bureaucratic inertia, vested interests and the many competing demands for the US attention and focus”.

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The USSC analysis suggests people in the US are hesitant about sharing technology, like nuclear submarine capability, with allies, including Australia (35% of respondents said it was acceptable to share with Australia).

The new analysis does show there is bipartisan consensus in the US that China is a major problem. New research from another leading Australian foreign policy thinktank, the Lowy Institute, to be released on Wednesday, looks at China’s future growth trajectory.

A paper co-authored by Lowy’s lead economist, Roland Rajah, says China will likely experience a substantial long-term growth slowdown owing to demographic decline, the limits of capital-intensive growth, and a gradual deceleration in productivity growth.

Rajah suggests annual economic growth in China will slow to about 3% by 2030 and 2% by 2040, while averaging 2–3% overall from now until 2050. The country remains on track to be the world’s largest economy, “but it would never enjoy a meaningful lead over the US and would remain far less prosperous and productive per person even by mid-century”.