From wiki:
In light of apparent systemic risks facing the banking system, the adequacy of FDIC’s financial backing has come into question. Beyond the funds in the Deposit Insurance Fund above and the FDIC’s power to charge insurance premia, FDIC insurance is additionally assured by the Federal government. According to the FDIC.gov website (as of January 2009), “FDIC deposit insurance is backed by the full faith and credit of the United States government”. This means that the resources of the United States government stand behind FDIC-insured depositors.”[35] The statutory basis for this claim is less than clear. Congress, in 1987, passed a non-binding “Sense of Congress” to that effect,[36] but there appear to be no laws strictly binding the government to make good on any insurance liabilities unmet by the FDIC.
Yes if life gets really bad FDIC will print the money to cover withdraws,UNTIL it managed to liquidate the assets of the banks it took over. Again if you don’t want it happening,you should be pro Gov making sure that there is no major collapse.