HARRISBURG, Pa. – A tough new voter identification law championed by Republicans can take effect in Pennsylvania for November’s presidential election, a judge ruled Wednesday, despite a torrent of criticism that it will suppress votes among President Obama’s supporters and make it harder for the elderly, disabled, poor and young adults to vote.

Commonwealth Court Judge Robert Simpson said he would not grant an injunction that would have halted the law, which requires each voter to show a valid photo ID. Opponents are expected to file an appeal within a day or two to the state Supreme Court as the Nov. 6 election looms.

“We’re not done, it’s not over,” said Witold J. Walczak, an American Civil Liberties Union lawyer who helped argue the case for the plaintiffs. “It’s why they make appeals courts.”

The Republican-penned law — which passed over the objections of Democrats — has ignited a furious debate over voting rights as Pennsylvania is poised to play a key role in deciding the presidential contest. Plaintiffs, including a 93-year-old woman who recalled marching with Martin Luther King Jr. in 1960, had asked Simpson to block the law from taking effect in this year’s election as part of a wider challenge to its constitutionality.

Republicans defend the law as necessary to protect the integrity of the election. But Democrats say the law will make it harder for people who lack ID for valid reasons to vote.

Opponents portray the law as a partisan scheme to help the Republican challenger, former Massachusetts Gov. Mitt Romney, beat Obama. Their passionate objections were inflamed in June when the state’s Republican House leader boasted to a Republican gathering that the new photo ID requirement “is going to allow Gov. Romney to win the state” in November.

Simpson, a Republican, didn’t rule on the full merits of the case, only whether to grant a preliminary injunction stopping it from taking effect.

In his 70-page opinion, Simpson said the plaintiffs “did an excellent job of ‘putting a face’ to those burdened by the voter ID requirement,” but he said he didn’t have the luxury of deciding the case based on sympathy. Rather, he said he believed that state officials and agencies were actively resolving problems with the law and that they would carry it out in a “nonpartisan, even-handed manner.”

The law, he said, is neutral, nondiscriminatory and applies uniformly to all voters. Speculation about the potential problems in issuing valid photo IDs or confusion on Election Day did not warrant “invalidation of all lawful applications” of it, he wrote.

Plus, more harm would result from halting the law, he said.

“This is because the process of implementation in general, and of public outreach and education in particular, is much harder to start, or restart, than it is to stop,” Simpson wrote.

At the state Supreme Court, votes by four justices would be needed to overturn Simpson’s ruling. The high court is currently split between three Republicans and three Democrats following the recent suspension of Justice Joan Orie Melvin, a Republican who is fighting criminal corruption charges.

The original Republican rationale for the law — to prevent election fraud — played little role in the court case. Government lawyers acknowledged that they are “not aware of any incidents of in person voter fraud.” Instead, they insisted that lawmakers properly exercised their latitude to make election-related laws.

Republican Gov. Tom Corbett signed the law in March after every single Democratic lawmaker voted against it.

At issue is the requirement that all Pennsylvania voters produce a valid photo ID before their ballot can be counted, a substantial change from the law it was designed to replace. That law required identification only for people voting in a polling place for the first time and it allowed nonphoto documents such as a utility bill or bank statement.

Some of the people who sued say they will be unable to vote because they lack the necessary documents, including a birth certificate, to get a state photo ID, the most widely available of the IDs that are valid under the new law.

The lawyers who provided free legal representation to the plaintiffs also warned that it will be difficult for many others to get a valid ID, and they presented testimony about workers at Department of Transportation license centers who appeared uninformed about the requirement to issue free nondriver photo IDs.

In addition, some voters won’t know about the law until they get to the polls, and long waits will result while untrained election workers struggle to carry out a complicated and unnecessary law amid the traditionally larger turnout in presidential elections, they argued.

Lawyers from the attorney general’s office, which defended the law, pointed out that the state is planning to begin issuing a special photo ID card for registered voters who are unable to get a PennDOT-issued ID and lack other acceptable photo IDs, such as passports or active-duty military IDs.

In addition, they say the state is rolling out a public relations campaign to make people aware of the law.

The Department of State, which oversees elections in Pennsylvania, has not produced any kind of study or survey that estimates the number of people without a valid photo ID that is required by the law.

Meanwhile, Obama’s Department of Justice is looking at whether the new law complies with federal laws and has asked the state’s top election official and a chief supporter of the law for a long list of information about it.