MOST Americans say the war in Iran has not been worth fighting, according to a damning new poll published on Thursday.

The new Associated Press-Norc Centre for Public Affairs Research poll also shows that approval ratings for the country’s far-right president, Donald Trump, are continuing to plummet.

The results are a stark repudiation of Mr Trump’s conduct of the conflict, which has dragged on far longer than he originally predicted.

About two-thirds of US adults say the war with Iran, which began on February 28, has not been worthwhile. That includes the vast majority of Democrats and independents, as well as about 37 per cent of Republicans.

The poll was conducted July 23-27, as the US and Iran paused attacks following a nearly two-week escalation in the war.

During the escalation, the US targeted Iranian military and commercial sites while Iran attacked US military facilities in the Middle East.

Since the illegal and unprovoked war began, 18 US service members have been killed.

The survey reinforces how unpopular the Iran war has become at home, a real problem for congressional Republicans ahead of November’s mid-term elections.

Just 28 per cent of US adults now approve of how Mr Trump is handling Iran, a sharp decline from 34 per cent last month.

Even Republicans appear to be increasingly unhappy with the prolonged conflict. Roughly 61 per cent of Republicans approve of how Mr Trump is handling Iran, plummeting from 71 per cent in June.

Mr Trump’s overall approval rating is at 33 per cent, well below where he stood at this point in his first term.

There appears to be little appetite among Americans for a prolonged conflict with Iran.

Only about two in 10 US adults want to continue the conflict, while about three in 10 say the US should pause military action and seek a renewed ceasefire through negotiations.