US inflation rose to an annual rate of 3.7% in September, up from 3.4% in August, the Bureau of Labor Statistics reported on Wednesday.

The reading is the highest since May, when annual inflation reached 4.2%. Consumer prices climbed 0.6% from August, while core inflation, which excludes food and energy, rose 0.3% during the month to an annual rate of 2.6%.

Gasoline accounted for more than half of the overall price increase and cost 34% more than a year earlier. Fuel oil prices were up 74% year on year, and air travel was 22.4% more expensive.

It is the final inflation report before the US midterm elections. Polls show widespread dissatisfaction with the Trump administration over living costs, leaving Republicans to face voters as inflation reaches its highest rate since the spring.