Senate Republicans on Tuesday passed the largest cuts to Medicaid since the program began in the 1960s, a move that would erode the social safety net and cause a spike in the number of uninsured Americans over the next decade.

The tax and spending bill is projected to cost more than $3 trillion during that time, but it would be partially paid for with about $1 trillion in cuts to Medicaid.

Almost 12 million lower-income Americans would lose their health insurance by 2034, according to the Congressional Budget Office (CBO).

It still needs to pass the House again, where some moderate Republicans have expressed concerns about the cuts.