So far Democrats’ generic-ballot lead has closely tracked prices at the pump, with about a two-week lag. This suggests that Democrats’ edge should continue to grow: a simple model based on the year-to-date relationship predicts that it will reach 7.7 points on October 1st. A recent, unsuccessful push from some Republican members of Congress to suspend the federal tax on petrol until 2027 shows that the party is well aware of the toll Mr Trump’s war in Iran is inflicting on their prospects.