PORTLAND – A panel of federal judges expects that Maine’s Legislature will redraw the boundary between the state’s two congressional districts by Sept. 30, and that the Maine Supreme Judicial Court will finish the work by Nov. 15 if lawmakers cannot complete the task in time.

If the Legislature and the state Supreme Court do not adhere to the deadlines, the federal judges will reapportion Maine’s congressional districts before Jan. 1 — the date when nominating petitions become available to congressional candidates.

The panel set the deadlines and outlined the procedure in an order issued Wednesday.

If state officials don’t appear to be working fast enough to meet their deadline, the judges may impose a new schedule to make sure the judges themselves are able to complete redistricting by the end of this year.

The judges ruled earlier this month that the current apportionment is unconstitutional because of population disparities revealed in the 2010 census, and that the congressional districts must be redrawn in time for the 2012 election.

Under its current system, Maine would have made its next readjustment in 2013.

State officials were sued by two Cape Elizabeth residents — William DeSena and Sandra Dunham — who argued that their votes would be diluted if the districts weren’t redrawn to reflect the southward population shift. The census showed that the population of the southern 1st Congressional District had grown to 668,515 while the 2nd District’s population was 659,848.

The plaintiffs and the defendants — Gov. Paul LePage, Senate President Kevin Raye, House Speaker Robert Nutting and Secretary of State Charles Summers — agreed that it would be unconstitutional to go into the 2012 election without readjusting the districts. The Maine Democratic Party, an intervenor in the case, argued that the integrity of a methodical, bipartisan process was at risk.

The judges — Bruce Selya, D. Brock Hornby and George Singal — ruled that the state must strive toward “precise mathematical equality” and make the districts “nearly as equal as is practicable under all the circumstances.”