Donald Trump has promised not to attack Iran before November’s US midterm elections, outlining a pause on the protracted war he has struggled to end after almost eight months.

In a Truth Social post on Thursday, Trump said Washington was “having productive discussions with the Islamic Republic of Iran”, which he claimed was “in very bad condition, both Economically and Militarily”.

The strait of Hormuz, through which roughly a fifth of the world’s oil and liquefied natural gas passed through before the war, was all but closed after the US and Israel struck Iran in late February.

On Thursday, however, Trump suggested that oil was moving through the strait in record volumes: “22 Million Barrels, last night alone,” he claimed, “with not one barrel coming from, or going to, Iran”. The figure could not be independently verified.

“We will not be attacking Iran at any time prior to the Midterm Elections to be held in the United States on November 3rd,” Trump wrote. “IRAN WILL NOT HAVE A NUCLEAR WEAPON!”

The US first imposed a blockade on the strait of Hormuz in April after talks in Islamabad collapsed, and reinstated it in July following a short-lived June deal to end the fighting. Fighting flared again in early September, when US forces struck rocket launchers on Iran’s Larak Island and Tehran responded with missiles aimed at American military bases in Jordan and the United Arab Emirates.

Trump’s public position on the elections has shifted over the past month. On 2 September, as the US exchanged fire with Iran for the first time in weeks, he told reporters he was “not affected by the election”, adding that he was not on the ballot himself but intended to help his party.

A week later, before heading to the Republican “midterm convention” in Dallas, he said he expected the war to end almost as soon as the voting was over, and accused Tehran of holding out in the hope that a change of power in Congress would leave it free to pursue a nuclear weapon. He also conceded that US oil prices were unlikely to fall before polling day.

A Reuters/Ipsos survey from late September found that only about a third of Americans approved of the strikes on Iran, while more than four in five expected the conflict to last for an extended period, and that approval for Trump among Republicans had fallen from 82% to 73% in a week.

Polling averages now show Democrats leading Republicans by roughly nine points on the generic congressional ballot, according to forecaster Nate Silver, the widest margin of this election cycle.

The Wall Street Journal reported in September that JD Vance, the US vice-president, and secretary of state Marco Rubio had privately warned Trump the conflict could extend through the remainder of his presidency.

Trump’s post did not say what the US would do after 3 November.