Diane Lim Rogers, the chief economist at the Concord Coalition, an Arlington, Virginia-based group that advocates for deficit reduction, said she was encouraged by the letter, though the group didn’t mention a specific revenue target. Rogers said the letter places a tax overhaul next to entitlement spending as part of the work for the joint committee. That’s the same formula used by bipartisan groups that have called for tax increases as an element of deficit reduction.

“What they’re saying very carefully is that there are ways to raise revenue that are not harmful to the economy,” said Rogers, a former Democratic staff member on the Ways and Means Committee.