A ballot measure to change the process for drawing political districts -- a power that has long protected incumbents and preserved party dominance around New York -- has split major good government groups.

In November, voters will decide on a constitutional amendment, Proposition 1, that would set up a panel to handle the drawing of legislative districts for members of the Assembly, Senate and Congress beginning in 2020. It was born from a political deal in 2012 that allowed lawmakers to handle their own political boundaries for the next 10 years in exchange for the amendment, which Citizens Union, a good government group, backed.

With the amendment now ready for voters, Dick Dadey, Citizens Union's executive director, said the proposal would wrest a key source of power from lawmakers through a panel of appointees. The proposal also has support from the League of Conservation Voters.

"We believe that after 50 years of failure and given a rare opportunity to fix this rigged process, New Yorkers should not let this opportunity pass," Dadey said in a conference call with reporters yesterday. "Reform is never an absolute process it's an incremental process."

Common Cause New York, however, feels the proposal keeps the process rigged. NYPIRG, a public interest organization, has also been critical of the amendment.

A state judge last month also gave grist to opponents of the amendment when he agreed that there is nothing "independent" about a 10-person panel whose members are picked by the legislative leaders and their proxies. Further, lawmakers can still devise their own maps "according to the established principles" of redistricting if they reject the panel's recommendations twice.

"Spin it anyway you like, but after the judge's ruling, it's impossible to claim that Proposition 1 would 'unrig' the system," said Susan Lerner, director of Common Cause New York. "New Yorkers understand that this proposed commission would actually make a bad situation worse."