Redistricting panel to release its plan for the Legislature

“The legislative districts have occupied the bulk of our time,’’ he said.

Senior legislative sources said the committee is still struggling to come to a decision on its most difficult political task.

Moran and his Senate counterpart, Stanley C. Rosenberg of Amherst, with the consent of their leadership in each branch, must determine which two of the 10 incumbent Democratic members of Congress will have to face off in the 2012 elections. The state has lost one congressional seat because its population growth has not kept pace with other regions of the country.

The Globe reported this week that the focus of the committee has been to either merge the district of Stephen F. Lynch of South Boston with that of William R. Keating of Quincy, forming a South Shore-based district that could extend through Cape Cod to Provincetown, or to abolish one of the two Western Massachusetts districts held by John Olver of Amherst and Richard Neal of Springfield.

According to sources with knowledge of the committee’s work, the struggle is inflamed by long-held regional resentments.

The Boston political establishment feels that the western counties, which have lost population, require only one congressional seat, while those west of Worcester resent the domination of the eastern regions of the state.

To abolish Olver’s First District would be a difficult task for Rosenberg, who is a former aide to Olver, as well as a close friend.

Rosenberg would also have to answer to his Western Massachusetts constituency if the redrawn congressional map were to eliminate one of the region’s districts.