Republicans are ramping up campaign spending ahead of the US midterms, but late advertising buys and high costs could limit the impact of their $1 billion war chest. Some Republican strategists worry much of the money is being spent too late Key points and original sources are listed below.

• Republicans are ramping up campaign spending ahead of the US midterms, but late advertising buys and high costs could limit the impact of their $1 billion war chest.S1

• Some Republican strategists worry much of the money is being spent too lateS2