The U.S. Supreme Court has said that under the one-person, one-vote principle, all election districts must have close to the same size of population. A group representing Latinos joined the suit, saying their numbers had increased by a wide margin across the state since 2001 - by 45 percent in Philadelphia.
The issue of old maps arose after the Pennsylvania Supreme Court, by a 4-3 vote, rejected a plan that would have brought maps up to date to reflect the 2010 census.
The state court said the plan by a Legislative Reapportionment Commission - criticized by Democrats as heavily gerrymandered - did not pass state constitutional muster. It said the plan improperly broke up counties, municipalities, and Philadelphia wards that should have been kept in single districts unless "absolutely necessary."
Republican leaders said Wednesday that they hoped the five-member commission could vote on a new plan Feb. 22.
Democrats argued, however, that it was too late for the primary. A new plan, a public comment period, and an appeal period would take from 90 to 120 days, they said.
The deadline for primary candidates to file nominating petitions is next Thursday.
Surrick rejected a request from Senate Majority Leader Dominic Pileggi, House Speaker Sam Smith, and House Majority Leader Mike Turzai, among others, to issue a temporary retraining order against the old maps.
He also declined a request for a three-judge panel to take a longer look at the case.
"To enjoin the 2012 election from proceeding under the 2001 plan would leave the Pennsylvania primary in a state of unacceptable uncertainty," he said.
Surrick noted that with presidential and congressional balloting this year, the issue was of concern beyond Pennsylvania.
Cliff Levine, a Pittsburgh attorney who argued against the Republican position on behalf of Democratic legislative leaders, said Wednesday that Rick Santorum, in particular, might want the primary to go ahead as planned.
Levine said that after his nominating-process victories this week in Minnesota, Missouri, and Colorado, the former Pennsylvania senator probably can't wait to come home for a vote.
"He wants to go ahead and have a primary in Pennsylvania, and not have this delayed," Levine said.
Kathleen Gallagher, an attorney for Turzai, noted that it was still within the purview of the legislature to set a new primary date.
Republicans, who control both houses, did not say Wednesday if that was part of their thinking.
"We are reviewing our legal and legislative options," Pileggi and Turzai said in a joint statement.
House Democratic leader Frank Dermody called Surrick's ruling "a victory for the people of Pennsylvania."
"The public deserves an orderly election process," he said.
Contact staff writer Tom Infield at 610-313-8205 or email@example.com.