US inflation rose by more than expected in the year to September, according to official figures, in the final data release before the midterm elections next month.
The pace of price rises increased to 3.7%, up from 3.4% in the 12 months to August.
Inflation was above forecasts, driven by higher gasoline prices which have spiked following disruption to Middle East energy supplies due to the US-Israel conflict with Iran.
The elections are being fought over cost of living pressures across the US.
Inflation is the rate at which the price of products or services increase over time.