Initial proposals from Washington's redistricting commissioners created a patchwork needing significant compromise.

An agreement has been reached between the four voting members of the state redistricting commission on a new map of Washington State’s Congressional districts, a source with the Washington State Redistricting Commission confirmed Tuesday afternoon.

Details about the map and how the new boundaries could affect incumbents or candidates are not being discussed in advance of tomorrow anticipated public unveiling. The new district lines will reapportion the state’s growing population to account for shifts noted in the 2010 U.S. Census and make room for a new 10th Congressional District.

When the map is revealed, most eyes will focus on key battlegrounds in Western Washington, specifically the districts of incumbent Reps. Dave Reichert (R, WA-08), Adam Smith (D, WA-09), Jay Inslee (D, WA-01), and Jaime Herrera Beutler (R, WA-03).

Population trends in the Greater Puget Sound region – relative to state growth, the Olympia Peninsula and Seattle have been shrinking compared to East King County, and Pierce and Clark Counties – have made political fortress-making a more challenging endeavor for Democrats. Speculation has persisted that voters in long-held Democratic precincts could be exposed to new Republican leadership as the 6th Congressional District home of Rep. Norm Dicks (D, WA-06) seeks to preserve a power base on friendlier soil in Central Puget Sound.

The district of Rep. Jay Inslee (D, WA-01) is another flashpoint of interest. Inslee’s candidacy for governor makes the 1st Congressional District an open seat and the final map could draw in or out a number of challengers in both parties who have expressed interest replacing him.

Though conservatives in the 2nd Congressional District have looked forward to a rematch of the 2010 race between incumbent Rep. Rick Larsen (D) and Republican John Koster, it still remains possible that the popular challenger could be drawn into the 1st. Inslee’s challenger in 2010 – Republican James Watkins – has also indicated interest in running again in the 1st.