Bernie Sanders wrote:President Clinton did and the deficit was shrinking quickly.
A common falsehood. Clinton was doing some interesting math, reducing the "public debt" but increasing the amount of debt that the government borrows from itself.
SourceUnderstanding what happened requires understanding two concepts of what makes up the national debt. The national debt is made up of public debt and intragovernmental holdings. The public debt is debt held by the public, normally including things such as treasury bills, savings bonds, and other instruments the public can purchase from the government. Intragovernmental holdings, on the other hand, is when the government borrows money from itself--mostly borrowing money from social security.
Quote from CBS which no longer is online for verification.
"Over the past 25 years, the government has gotten used to the fact that Social Security is providing free money to make the rest of the deficit look smaller," said Andrew Biggs, a resident scholar at the American Enterprise Institute.
Social Security isn't the only trust fund in the federal budget. There are a number of others including the civil service retirement fund, federal supplementary medical insurance trust fund, unemployment trust fund, military retirement trust fund, etc. All of these trust funds, like Social Security, invest their surpluses in U.S. government bonds and increase intragovernmental debt. And like Social Security, their surpluses really shouldn't count toward a "surplus" because the excess money they contribute to federal coffers actually has to be borrowed by the government from the trust funds.