US debt ceiling talks collapse as Republicans refuse to budge.

Republican negotiators have walked out of talks with Democrats over raising the US debt ceiling, increasing the risk of a government shutdown. The US Treasury has warned that the government will run out of money to pay its bills by mid-October if the debt ceiling is not raised. Republicans have refused to support an increase in the debt ceiling without corresponding spending cuts, while Democrats argue that the debt ceiling must be raised to pay for spending that has already been approved by Congress.