A Pennsylvania judge on Tuesday delayed full implementation of a highly contested state law requiring strict photographic identification to vote in next month’s election, saying that the authorities had not done enough to ensure that potential voters had access to the new documents.

The judge, Robert Simpson, who upheld the law in August when it was challenged by liberal and civil rights groups, was instructed by the state’s Supreme Court two weeks ago to hold further hearings. He was told to focus on the question of whether enough had been done to ensure “liberal access” to the picture ID cards or alternatives.

Judge Simpson said in his Tuesday ruling that for the presidential election of Nov. 6, voters in Pennsylvania could be asked to produce the newly required photo IDs, but if they did not have them could still go ahead and vote. The decision could be appealed to the State Supreme Court.

“While we’re happy that voters in Pennsylvania will not be turned away if they do not have an ID, we are concerned that the ruling will allow election workers to ask for ID at the polls and this could cause confusion,” said Penda D. Hair, co-director of Advancement Project, one of the groups that challenged the law. “This injunction serves as a mere Band-Aid for the law’s inherent problems, not an effective remedy.”

The Pennsylvania law, passed in the spring without any Democratic support, is one of 11 similar laws around the country passed by Republican-dominated legislatures. The laws’ backers say they are trying to ensure the integrity of the electoral process by preventing fraud. But Democrats accuse them of seeking to suppress the votes of the poor and members of minority groups who tend to have neither the needed ID nor the means to go to state offices and obtain one and who tend to vote Democratic.

In opinion surveys, substantial majorities of Americans back the voter ID requirements despite the fact that repeated efforts to demonstrate the existence of in-person voter fraud have shown there to be very little of it.

Pennsylvania is one of a number of swing states that could make the difference in the presidential race between President Obama and Mitt Romney, the Republican candidate, especially if the count is close. Increasingly, however, Mr. Obama, who won Pennsylvania in 2008, has been pulling far ahead of Mr. Romney in key states. A Quinnipiac/New York Times/CBS News poll last week showed Mr. Obama ahead in Pennsylvania by 12 points.

With a month left before the election, voter ID requirements around the country were looking far less significant than they once had. They have been taken off the table in Texas, Ohio and Wisconsin although the Wisconsin law remains under judicial review. The Justice Department permitted New Hampshire to go ahead with its voter ID law, but those who do not have the required document will be permitted to vote and have a month to verify their identity.

The Pennsylvania law’s challengers said that their focus over the coming month would be to press the state to alter its voter education campaign to make clear that no picture ID is in fact required to vote in the upcoming election.

“This is a big win in that no one will be turned away on Election Day because they don’t have the new strict voter ID,” said Benjamin D. Geffen, a lawyer with the Public Interest Law Center of Philadelphia, which took part in the law’s challenge. “The state has a large budget to spend on advertising this fact, and we want to make sure it does it.”

Nick Winkler, director of public relations for Pennsylvania’s department of state, said there would indeed be a change in what voters were told and in how poll workers would be trained for next month.

“Our education campaign is in full swing, and all we have to do is retool it from talking about requiring voter ID to requesting it,” he said. “Poll worker training has not begun in some counties and will now take this into account as well.”

Mr. Winkler said the state had not yet decided whether to appeal the decision.

He said that a total of 13,000 alternative ID’s had been issued by the state purely for the purpose of voting and that state colleges and universities were updating their student ID cards to make them eligible forms for their holders to use at the polls. The state law permits about eight kinds of ID to be shown at the polls.

But Judge Simpson said in his Tuesday decision that the issuing of the new documents across the state had not been fast enough.

“I expected more photo IDs to have been issued by this time,” he wrote. “Under these circumstances, I am obliged to enter a preliminary injunction” preventing the law from being fully implemented.

He said he did not consider the mere asking for photo ID to be a problem, only the availability of the documents and only for the coming election. During two days of hearings last week he heard stories of voters waiting hours to obtain their IDs and being forced to return more than once to the appropriate office.

He said that the challengers to the law argued that the state had not made provisions for the ID to be obtained easily even after November 6th and he would begin planning for a trial to examine the need for a permanent injunction against the law. He added that if he had misunderstood the Supreme Court’s instructions on this point, he would appreciate further guidance from it.

At the State Supreme Court hearings, the lawyers for the liberal groups said that, in theory, a voter ID law could pass constitutional muster if the document were truly easily available, but that Pennsylvania had not taken steps to ensure that as of now.