State Democratic leaders say they hope to block any attempt by Republicans to delay the April 24 Pennsylvania primary.

Senate Minority Leader Jay Costa and House Minority Leader Frank Dermody said Sunday that they would oppose a GOP lawsuit to be heard Monday in federal court in Philadelphia.

The GOP is seeking an injunction to halt use of out-of-date election maps in the primary for the state's 203 state House districts and 50 Senate districts.

After the Pennsylvania Supreme Court invalidated a new redistricting plan, calling it unconstitutional, Senate Majority Leader Dominic Pileggi, a Delaware County Republican, floated the possibility of moving the primary so a commission could create new redistricting maps.

The Republicans argue that the U.S. Supreme Court's one-person, one-vote ruling requires a remapping after every decennial census so that all districts are about the same size in population.

Clifford Levine, a lawyer representing Costa and Dermody, said he would move to dismiss the GOP action.

Costa, Dermody, and Pileggi - along with House Majority Leader Mike Turzai - are members of the Legislative Reapportionment Commission.

The Democrats argue that the primary campaign is already under way. Rather than delay the primary, they said, the old maps should be used - something that two state Supreme Court justices suggested might be necessary.

"They [the GOP] should not be able to hijack this election," Costa said in a conference call with reporters. "The court was very clear in its opinion. We have to respect and honor that."

Said Levine: "Federal courts have indicated that the states should be given deference in developing redistricting plans, and that a federal court should not interfere with an impending election, particularly where there is no other plan yet available."

He said that it would take at least 90 days for a final map, and at least another 90 days to establish candidates under new boundaries. It is "physically and legally impossible" to come up with a plan before the April 24 primary, he said.

Congressional district maps are not affected by the court action.

GOP legislative leaders say they hope to vote on a plan by Feb. 22, but the state court has said a new plan will still have to go through all of the normal steps, including a 30-day public-comment process and a 30-day appeals process.

Turzai, in a memo to GOP House members Sunday, said they should assume, for now, that the primary will be held with the old maps.

"Nothing in the [state court] opinion changes how candidates for the House or Senate should collect petition signatures," he said.

Candidates have until Feb. 16 to file nominating petitions. Turzai said: "The only logical conclusion which can be drawn from the opinion is that candidates should continue collecting signatures in areas in which districts coincide with [both] the 2001 lines and 2011 lines."