Yes, under two conditions.
A borrower can consolidate existing consolidation loans into a new Direct Consolidation Loan if the borrower includes at least one other FFEL or Direct Loan into the new consolidation loan.
A borrower can conslidate a single FFEL consolidation loan if the FFEL consolidation loan is in default status or has been submitted to a guaranty agency for default aversion by the borrower's loan holder.
(Source: loanconsolidation.ed.gov)
