Hurricane Sandy-related claims are pouring into the troubled government-run National Flood Insurance Program — and Congress is girding for revived battles over the program’s debts.

The NFIP, America’s only provider of flood insurance, faces an estimated $6 billion to $12 billion in new claims from Sandy, according to the Federal Emergency Management Agency.

The NFIP, which is about $18 billion in debt after Hurricane Katrina, has only $2.9 billion left in borrowing authority, Edward Connor, FEMA’s deputy associate administrator for federal insurance told a meeting last week, according to news reports.