Sens. Mark Warner, D-Va., Kent Conrad, D-N.D., Richard Durbin, D-Ill., Saxby Chambliss, R-Ga., and Mike Crapo, R-Idaho, have been meeting for several months quietly to forge an agreement that would parallel recommendations made by the White House deficit reduction advisory committee, The Wall Street Journal reported Tuesday.
But the group had gotten stuck on entitlement issues, The Hill newspaper said.
"We can't bridge the gulf of where we need to go on mandatory spending. I don't see that there's going to be any fruition in continuing them at this time," said Coburn, who arrived at a group meeting Tuesday without any staff members and left within 10 minutes.
The so-called Gang of Six, now a diminished Gang of Five, would still keep trying, Conrad told Politico.
"We're still talking, still trying. This is not easy stuff," Conrad said.
The group was aiming, roughly, to cut the deficit by $4 trillion over a 10-year period.
For Coburn, that meant including a discussion on Social Security reform. But Democrats in the group said they would discuss Social Security separately, not as part of a deficit reduction plan.
Coburn said leaving the group was "a recognition that we can't get there."