A congressional panel working on a plan to save financially troubled multi-employer pension funds is considering repeal of the so-called “last-man-standing” rule that has saddled companies that remain in the retirement plans with the outstanding benefit liabilities.

Sen. Rob Portman (R-Ohio) , who is on the 16-member bicameral committee, said the willingness of Democrats to consider eliminating that provision has helped drive progress in the talks, which he said he hoped could be concluded before Congress adjourns for the year....