A group of banks including JPMorgan Chase, Bank of America and Goldman Sachs is struggling to put together a $20 billion loan to Argentina

The group of banks, which also includes Citigroup, is seeking some type of guarantee or pledge to ensure they will get their money back, the people said. Bankers are waiting on guidance from the Treasury Department on what collateral Argentina would be able to provide for them or if Washington would plan to backstop the facility on its own, the people said.