Donald Trump’s approval rating fell to ​the lowest level of his presidency with an overwhelming majority of Americans concerned the United States’ war with Iran will last a long time, according to a Reuters/Ipsos poll that concluded on Monday.

Just 33 per cent of respondents in ​the four-day survey said they approved of the US president’s performance in the White House, while 64 per cent disapproved.

Trump’s approval rating, ⁠down from 35 per cent in a poll that closed earlier this month and lower ‌than ‌at ​any point in his current term, has now a tie with the lowest level of his first term reached in December 2017.

After returning to the ⁠White House last year with ​just under half the country approving of his ​presidency, Trump’s popularity this year took a hit after he ordered strikes on Iran alongside US ‌ally Israel.

The ensuing conflict has paralysed ​a fifth of the global oil trade, triggering a surge in the price of ⁠petrol which is weighing on US households – ⁠and on Trump’s ​Republican allies defending congressional majorities in November midterm elections.

Donald Trump says Iran should surrender, threatens to bomb Oman ]

Trump, who campaigned on promises to keep inflation in check and avoid long-lasting wars, initially pledged the conflict with Iran would take a few weeks. He has argued the war was the only way to prevent Iran from developing a nuclear weapon that could threaten the world.

But Iran has proved resilient and has kept the oil trade through the Strait of ‌Hormuz largely bottled up ⁠even as the conflict has cooled.

About 80 per cent of Americans – including 87 per cent of Democrats and 71 per cent of Republicans – think US involvement in Iran “will go on for an extended ‌period of time,” the Reuters/Ipsos poll found.

Just 16 per cent said the conflict would likely end in a few ​weeks.

The Reuters/Ipsos poll, which was conducted online, gathered responses from ​1,166 US adults nationwide and had a margin of error of three percentage points in either direction.