The key lawmaker, who spoke on condition of anonymity, said it is unrealistic to think the 12 lawmakers on the panel will be able to agree to a budget-cutting deal as large as $3 trillion or $4 trillion, as some have urged it to do…

“We need to ‘go big’ and reach savings of more than $1.5 trillion to address long-term deficits,” Sen. John Kerry (D-Mass.), a panel member, said Tuesday. “We need to ‘go long’ and address our long-term budget issues.”

But the supercommittee member who spoke on background cast doubt on the ability of the panel to be so ambitious. There does not appear to be any consensus to cut Medicare payments to doctors, the Defense Department or other large programs with strong political support, the lawmaker said.