Congress has long directed the government to spend more money than it collects in taxes. That means the government has to borrow money to meets its obligations, which it does by selling Treasury securities.Treasury securities are a promise from the government that you if give it money now, it will pay you back with interest later. They have long been considered among the safest investments in the world.But now, the U.S. is flirting with not paying its bills by refusing to increase the amount of money that the government is legally allowed to borrow — its "debt ceiling."We explain the basics of how the system works and what the consequences might be if the ceiling is not raised and the government runs out of money.Previously on the podcast: Much Ado About Debt, Jan. 18This episode: White House correspondent Tamara Keith and political correspondent Kelsey Snell.The podcast is produced by Elena Moore and Casey Morell. Our editor is Eric McDaniel. Our executive producer is Muthoni Muturi. Unlock access to this and other bonus content by supporting The NPR Politics Podcast+. Sign up via Apple Podcasts or at plus.npr.org. Connect:Email the show at nprpolitics@npr.orgJoin the NPR Politics Podcast Facebook Group.Subscribe to the NPR Politics Newsletter.