Vance's position will lead to a broader debate on foreign policy.
Daniel Bush, BBC correspondent in Washington.
It is hard to recall recent and similar examples in which an established vice president spoke so openly and openly about his party's defeat in the midterm elections; He seems to want to separate himself from the president.
J. Dee Vance said any "honest discussion" about the party's future must begin with an acknowledgment that the Iran war has caused Republicans to lose control of Congress.
Mr. Trump acknowledged that the Iran war and rising gasoline prices played a role in that failure, but said he had no regrets about starting that conflict.
But Mr. Vance went one step further. The vice president said Republicans can talk about whether the war is worth its political costs.
He refused to explicitly express his opposition to the war; A war that he supported in his public positions for a long time. However, news reports indicate that he expressed his opposition to the war in closed meetings.
His words will spark a broader debate on the American right about Republican foreign policy in the post-Trump era.