The U.S. could lose its AAA credit rating from another major rating agency, Bank of America Merrill Lynch economists warned.

Failure by Congress to agree on a deficit reduction plan could signal a downgrade by either Moody's Investors Service or Fitch Ratings, BofA Merrill said in a report Friday.

The 12-member congressional super committee must reach a deal to cut $1.2 trillion by Nov. 23. 

"The 'not-so-super' deficit commission is very unlikely to come up with a credible deficit-reduction plan," wrote Ethan Harris, North American economist at BofA Merrill. "The committee is more divided than the overall Congress."

A top analyst for Moody's told Reuters they're also looking at the outcome of next year's presidential election and expiring Bush-era tax cuts.

The dire predictions come two months after Standard and Poor's downgraded the U.S. credit rating from  AAA to AA+.