WASHINGTON (AP) — As the summer driving season swings into full gear, states can expect a large pothole in their construction budgets if Congress doesn’t reach an agreement quickly on how to pay for federal highway and transit programs, President Barack Obama and his top officials are warning.

States will begin to feel the pain of cutbacks in federal aid as soon as the first week in August if lawmakers don’t act, Transportation Secretary Anthony Foxx said in a letter to states. That’s because the balance in the federal Highway Trust Fund is dropping and will soon go below $4 billion, the cushion federal officials say is needed for incoming fuel tax revenue to cover outgoing payments to states.