HARRISBURG — Pennsylvania state lawmakers, potential candidates and political strategists began a scramble to adapt on Thursday, a day after a state Supreme Court ruling threw out a map of legislative districts drawn up with the latest census figures.

Many were not waiting to see the details of the court’s reasoning in a written opinion that will not be available until next week, at the earliest, because the three-week period to circulate nominating petitions to get on the ballot has just begun.

The court voted 4-3 to declare the Legislative Reapportionment Commission’s map of 50 Senate and 203 House districts invalid, a decision that raised the real possibility it could be months or longer until a new plan is enacted.

Before the decision was announced late Wednesday, Rep. Nick Kotik thought he was facing a primary battle against a fellow Democratic incumbent in Allegheny County, but he immediately shifted gears to focus his efforts on running in his existing district.

The court said the 2001 map remains in force until a new one can pass muster.

“It was a shocker, I’ll say that,” Kotik said. “If you look at it strictly from a partisan viewpoint, it’s not supposed to go that way. Four is four and three is three, and that’s what I assumed it would be.”

There are four Republican justices on the seven-member court, but Chief Justice Ronald Castille, the Republican former district attorney of Philadelphia, sided with the three Democrats to reject the plan. It had been approved by the commission on a 4-1 vote, supported by the Republican leaders of the House and Senate, and House Democratic Leader Frank Dermody. The fifth member, an appointed judge, also a Republican, voted for it. Only Senate Democratic Leader Jay Costa voted “no,” and he challenged it in court.

Justice Max Baer, who voted to invalidate the new district map, said Thursday the justices and their staff were working on the opinion. He declined to say whether candidates should assume this year’s contests will be run under the 2001 map or a new one.

“We’re working as hard as we can, and if we get something out and the political powers and the secretary of the commonwealth think they can go on the new one, that’s up to them,” Baer said in a phone interview. “That’s none of our business. Our only job is to assess (whether) the commission’s plan meets constitutional criteria.”

He said the issues are the compactness of districts and the state constitutional requirement that municipalities do not get split up unless absolutely necessary.

The decision sent shock waves through the state’s political establishment, coming as it did in the early days of the two-year legislative election cycle.

“This is a new ballgame,” said Franklin & Marshall College political scientist Terry Madonna. “This is a huge decision that’s going to have significant repercussions.”

If the court demands minor changes, it’s possible the Legislative Reapportionment Commission could quickly produce new maps that, for example, would reunite a divided borough into a single district. But if the justices announce new standards for all districts, and require the commission to justify each of the more than 100 municipal splits in the rejected plan, the process could slow to a crawl. The primary is April 24.