US gasoline prices are hovering at four-year seasonal highs toward the November midterm elections, even as US President Donald Trump has called repeatedly for the Organization of Petroleum Exporting Countries to buoy prices higher.

Even though gasoline prices usually drop following peak summer demand season, they have not slipped as fast as expected, according to Jeanette Casselano, spokeswoman for the American Automobile Association.

The national price average was at $2.867 per gallon as of Wednesday, and that was its seasonal highest since 2014, according to AAA.

Fuel prices have climbed to a swell in crude oil prices. US crude futures have increased in part because of US sanctions influencing Iran’s petroleum sector, which have already slashed into the nation’s exports, according to market participants.

That has compelled others, including Saudi Arabia and Russia, to make up for the difference. The price of the global benchmark Brent reached a four-year high of $82.55 per barrel this week. Meanwhile, the US crude reached $72.78, which was its highest since July 11.

The sanctions are expected to take supply off the market the moment they go into effect in November. OPEC has ended a meeting on Sunday with no formal recommendation to bolster output.