Negotiations within the 12-member panel have been slowed down by an intense debate over the basic question of how to count the savings from any potential deficit-reduction deal.

With only weeks left before the bipartisan panel hits the congressionally mandated deadline for reporting its recommendations, lawmakers have yet to resolve the thorny question of what kind of baseline to use to score a deal, according to sources familiar with the talks.

The question is critical, because without agreement on the benchmark, it will be virtually impossible to agree on a package that could be moved to the Senate and House for final approval.