Joe Biden has not supported cuts to social security but has supported overall freezes to government programs in the past to address federal deficit.
In the past, while Biden supported freezing of social security, he also supported a reduction in other programs such as Medicaid and Veterans Programs, to control the growing federal deficit. Three main events highlight Biden's actions:
Between 1980-1990, Biden advocated for freezes in Social Security, Medicaid, and other state-run programs to control the growing federal deficit. In 1984, he co-sponsored a proposal with two other GOP senators to freeze federal spending, but it was defeated.
In 1995, the balanced-budget amendment which aimed to reign in the deficit was proposed. Part of the amendment called for legislation to reduce Social Security benefits. Initially, Biden voted against the inclusion of Social Security reduction in the amendment but ultimately voted for the balanced-budget amendment that included a reduction in social security benefits.
Biden sponsored a Senate Resolution Act in 2003 opposing cuts in the cost-of-living increases for Social Security. In 2011, Obama's Budget Control Act was initiated to reduce the deficit but Obama and Biden safeguarded social security.
Therefore, while Joe Biden has supported cuts to the social security system in the past, he has not singularly supported cuts to only social security but has advocated for reduced spending for various other programs.