Four Republican senators—Susan Collins, Lisa Murkowski, Rand Paul and Thom Tillis—joined Democrats in supporting a Senate resolution to curb President Donald Trump’s war powers over the conflict in Iran. The measure failed, as most Republicans backed Trump, but the defections highlighted growing tensions within the party as the war approaches eight months and becomes increasingly unpopular.

The resolution followed repeated concerns that the administration had exceeded a 60-day deadline for consulting Congress, although it was unlikely to become law after passing the House and facing a probable presidential veto. Republican divisions have widened amid rising petrol and diesel prices, reports of US bombs hitting an Iranian school, and electoral concerns, with several vulnerable Republican candidates calling for an immediate end to the fighting. Trump said electoral considerations would not influence his Iran policy, insisting that preventing Iran from obtaining a nuclear weapon remained his priority.