Paul blocked a push, introduced by Sen. Kirsten Gillibrand, D-N.Y., to sign off on the bill approved by the House in a 402-12 vote last week.
The bill would ensure the fund can pay benefits for 70 years.
While balking at the bill, Paul pointed to a need to get the $22 trillion national debt under control before adding any additional spending
It has long been my feeling that we need to address our massive debt in the country," he said.
“Any new spending we are approaching, any new program that’s going to have the longevity of 70, 80 years should be offset by cutting spending that’s less valuable.
“We need to at very least to have this debate.”
Gillibrand, a 2020 Democratic hopeful, said she was “disappointed” by Paul’s move to block the bill.
However, a spokesperson for Paul said the Senator is"not blocking anything," and instead is trying to figure out how to pay for it.
"Senator Paul is not blocking anything. He is simply seeking to pay for it. As with any bill, Senator Paul always believes it needs to be paid for. Senator Paul is simply offering an amendment, which other senators support, to pay for this legislation," a spokesperson told Fox News in a statement.