SYDNEY (Reuters) - Nearly half Australian adults would support their country distancing itself from the United States if Donald Trump became U.S. president, a poll suggests, as the New York billionaire tightens his grip on the Republican nomination race.

U.S. Republican presidential candidate Donald Trump speaks during a town hall interview on NBC's "Today" show in New York, April 21, 2016. REUTERS/Brendan McDermid

The telephone poll of 1,202 Australian adults found that 45 percent believed the country should distance itself from the U.S. “if it elects a president like Donald Trump”, said researcher the Lowy Institute, which commissioned the research.

Just 51 percent of Australians believed the country should remain close to the United States regardless of who became president in the Nov. 8 election, the lowest level of support in a generation.

“By allying ourselves with the United States ... we contribute to global security as well as our own,” said Lowy Institute executive director Michael Fullilove.

“That nearly half of Australians would seek to move away from America in the event of a Trump victory says something quite disturbing about the GOP front runner.”

Australia, New Zealand and the U.S. have been formal allies since signing the ANZUS treaty to protect the Pacific in 1951, and have been allies in most conflicts of the past century. Australia currently has troops in the Middle East to fight Islamic State alongside the United States.

The poll by the Lowy Institute, an independent policy think tank based in Sydney, was conducted between Feb. 26 and March 15.

It did not offer any insight into how Australians would want to distance themselves from the United States, nor did it specify a Donald Trump presidency - merely “a person like Donald Trump” becoming president.

But Australia’s sentiment towards the United States under Trump is weaker than it was under President George W. Bush in 2007, several years into the unpopular Iraq war. In what was considered a dip, 63 percent of Australians regarded the country’s alliance with the United States then as important to Australia’s security, Lowy said.

Just a year ago, 80 percent of Australians said the alliance with the United States was either “very” or “fairly” important, Lowy said.