In a lengthy post on social media platform X, Vance said the war was the reason for the defeat, adding that President Donald Trump had made a similar assessment the previous night.
“We know why we lost, and any honest conversation about where we go from here must start there,” Vance wrote.
He said that although voter turnout data showed Republican voters had participated in the midterm elections, many had not supported the party’s candidates.
Vance also acknowledged that the Republican Party had failed to communicate its economic message and policy narrative effectively.
Referring to recent polling data, the vice president said voters who had supported Trump in the 2024 presidential election were now primarily demanding action on four key issues: ending the war, addressing inflation, pursuing an America First policy and changing the United States' relationship with Israel.
Vance had reportedly expressed reservations about the prospect of war with Iran earlier this year, before Trump ordered US strikes against the country. He had reportedly warned that Washington could become entangled in a conflict that would be difficult to end.
The election results have also drawn attention to the Republican Party's foreign policy and domestic economic priorities, particularly among voters who supported Trump in 2024.
Meanwhile, US media reports have described Vance as one of the leading potential contenders for the Republican presidential nomination if he decides to run in the 2028 presidential election.