Are there other ways for the president to raise money besides borrowing?
Sovereign governments such as the United States can print new money. However, there's a statutory limit to the amount of paper currency that can be in circulation at any one time.
Ironically, there's no similar limit on the amount of coinage. A little-known statute gives the secretary of the Treasury the authority to issue platinum coins in any denomination. So some commentators have suggested that the Treasury create two $1 trillion coins, deposit them in its account in the Federal Reserve and write checks on the proceeds.
Other clever solutions may be found here.