AUSTIN, Texas — Texas’ strict voter ID law discriminates against minorities and the poor and must be weakened before the November elections, a federal appeals court ruled Wednesday, following claims that at least a half-million registered voters could have struggled to cast a ballot.

The ruling was a striking election-year victory for President Barack Obama’s administration, which took the unusual step of bringing the U.S. Justice Department into Texas to fight the case. U.S. Attorney General Loretta Lynch said the ruling affirmed that the 2011 law — which Texas enforced in three elections — abridged the right to vote based on race or color.

Republicans were dealt a second blow in as many days to a new breed of strict voter ID measures that limits the kind of photo identifications that are valid. On Tuesday, a federal judge in Wisconsin ruled that residents without a photo ID in that state will still be allowed to vote in November.

Elections experts widely agree that the Texas law, which accepted concealed handgun licenses but not college IDs, was the toughest in the nation.

Voters must still show identification at the polls in Texas under the decision by the New Orleans-based 5th U.S. Circuit Court of Appeals, which is regarded as one of the most conservative panels in the country. But a lower court is now instructed to devise a way for Texas to accommodate those who cannot.

“It’s a great day for civil rights across America, and it’s a critically important achievement for voters throughout Texas who have as of late been routinely mistreated by state leaders,” said Houston attorney Chad Dunn, who helped represent a team of Democrats and minority rights groups that challenged the law.

The 9-6 decision agreed with a lower court ruling that Texas had violated the federal Voting Rights Act. Elections experts have testified that Hispanics were twice as likely and blacks three times more likely than whites to lack an acceptable ID under the law.