US Vice President JD Vance has admitted that the war of aggression against Iran was a key factor behind the Republican Party’s defeat in the midterm elections, saying the war cost the party control of the Senate.

“The reason we lost is the war. The president himself said so last night,” Vance wrote in a post on X on Wednesday.

“If you’d like to argue it (war) was worth it, that losing the Senate for the next 6 years was worth it, then do so,” he added.

The vice president acknowledged that many voters who backed President Donald Trump in 2024 switched to Democrats over the war.

“The main problem is that many people who voted for Trump/Vance in 2024 voted for Democrats in 2026,” Vance claimed.

He predicted that there will be a lot of "infighting" and debates in Washington over why Republicans were defeated in the elections.

"One of the pollsters I really respect told me that our economic messaging wasn’t sharp enough down the stretch," he said.

"I’m sure that’s true. But the real reason we lost is obvious to almost everyone," Vance added, referring to the war against Iran.

His remarks came as other Republicans also pointed to President Trump’s policies, particularly the war on Iran, as a major factor in the party’s poor performance.

The war proved costly politically for Trump and his Republican allies in Congress because it drove up gas prices and fueled inflation, straining household budgets and turning cost-of-living concerns into a central issue that alienated voters.

The election results have been described by some Republicans as a rejection of Trump’s presidency.

Bill Miller, a top Republican lobbyist in Texas, called the outcome “a total, complete rejection of President Trump” and “a disaster of the first magnitude.”

‘Pride comes before a fall’: Iran warns Trump after Republican defeat in midterms

The Foreign Ministry spokesman says American voters have sent a clear message to President Donald Trump through their votes against his Republican Party in the US midterm elections.

The war has also fuelled voter frustration over rising living costs. Iran’s control of the strategic Strait of Hormuz and the disruption of shipping through the waterway have had a major impact on global oil prices, adding to economic pressures in the United States.

Exit-poll findings reported by Reuters showed that around two-thirds of voters blamed Trump for high prices, while approximately three-quarters said they were angry or dissatisfied with the direction of the country.

Trump’s backing of Israel has also become a source of domestic political division, amid growing public opposition to US military assistance and criticism of Washington’s foreign-policy priorities.

Democrats won control of both chambers of Congress in Tuesday’s midterm elections, ending Republican control of the legislature for the final two years of Trump’s presidency.