Incredible as it may seem, the US could actually default in its obligations.
https://www.nytimes.com/2021/09/26/business/economy/america-debt-limit-political-game.html
This is a problem that they need to address as soon as possible before it gets out of hand. I don't think raising the limit should be one of their top priority to pay existing bills. The US government has to learn good financial decision-making to avoid this kind of scenario. Surely they have their great accountants in the department of finance, it is just that the officials decided to take a wrong turn making a bad decision that cost this to happen. Hopefully, they'll be able to handle this. They are the US after all. They won't stumble that fast.