Consumer sentiment fell sharply in September as rising fuel prices fueled inflation concerns and weakened Americans' outlook for the economy.

The University of Michigan's final consumer sentiment index fell 7% to 48.1, its lowest level in four months, although it was slightly higher than the preliminary reading of 47.8.

Consumers now expect prices to rise 4.6% over the next year, up from 4% in August. Five-year inflation expectations rose to 3.4%.

The deterioration crossed party lines. Republican sentiment fell 5.9% to 77.2, while Democratic sentiment dropped 11.4% to 35.6. Independent sentiment declined 0.6% to 47.7.

University of Michigan survey director Joanne Hsu said consumers broadly agree that the economic outlook has weakened, citing higher fuel prices and renewed trade concerns.

Despite the decline in confidence, consumer spending has remained resilient, supported by low unemployment and relatively low jobless claims. The survey also found that some consumers are accelerating purchases of durable goods to avoid expected price increases.

The report comes as gasoline and diesel prices have climbed sharply, adding another source of pressure for Americans already facing elevated inflation expectations.