US hits borrowing limit, kicking off fight between Republicans and Democrats – as it happened

• Biden and Democrats want to raise limit without conditions
• What is the US debt ceiling and what happens if it isn't raised?
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Urban Institute economist Len Burman has a reality check for those in Congress flirting with not raising the debt ceiling.

A default could undermine the America's pre-eminence in global markets, where the dollar is used as many countries' dominant reserve currency. But more immediately, it would actually force Washington to spend even more, because a default would drive up interest rates, forcing the government to shell out more money to owners of its trillions of dollars in debt: