Congress is the monopoly issuer of our currency via Article 1: Section 8 of our constitution. It controls all transactions between itself and its suppliers. It has no need to get its own currency from anyone else, including taxation or lending. When money is created from thin air it materializes in accounts at the Fed, making it appear as if the Fed is creating the money.

It doesn't, except as an accounting procedure that is nothing but marking up accounts via keyboard entries as it is directed by Treasury and Congress. It shares a balance sheet with Treasury, meaning that any profits it makes above its expense and a pre-set fee are returned to Treasury to be applied to the debt and destroyed.

The Fed is a pseudo private institution that maintains a line between government and the privates sector, but rest assured that it doesn't "loan" any money to the US government. Its only control lies in its ability to set interest rates for its member banks in monetary policy, not fiscal spending. It simply acts as the clearing bank for Treasury. Does your bank "create" the money in your checking account?