Politico reported that with fighting continuing between the United States and the Iranian government, concerns among Republicans about the political consequences of the war have grown.

The outlet wrote that increases in fuel prices, the deaths of American servicemembers, and the unclear prospect of an end to the fighting have turned the war into a challenge for Donald Trump, the U.S. president, and the Republican Party ahead of the midterm elections.

According to Politico, European allies of the United States have also declined to join Washington’s naval mission in the Strait of Hormuz and have called for a ceasefire before any joint action; a development that points to a split with the U.S. over how to manage the crisis.