AUSTIN, Texas — The U.S. Justice Department said Monday it is abandoning its longstanding opposition to a key aspect of Texas’ toughest-in-the-nation voter ID law, costing voting rights groups their most important ally and possibly encouraging other conservative states to toughen their own election rules with President Donald Trump in charge.

It’s a dramatic break from the agency’s position under President Barack Obama, which spent years arguing that the voter ID law passed in 2011 by Texas’ Republican-controlled Legislature was intended to disenfranchise poor and minority voters.

“It’s a complete 180,” said Danielle Lang of the Washington-based Campaign Legal Center. “We can’t make heads or tails of any factual reason for the change. There has been no new evidence that’s come to light.”

The law requires voters to show one of seven forms of state-approved photo identification — gun permits are acceptable but college IDs are not. Voting rights activists sued, and the case returns to court Tuesday in Corpus Christi, Texas, before U.S. District Judge Nelva Gonzales Ramos.

Justice Department spokesman Mark Abueg said that although the Justice Department will no longer argue that the law was intended to discriminate against minorities, it doesn’t plan to withdraw from a portion of the lawsuit that argues that the law had the effect of discriminating against them.

The “intent” versus “effect” distinction is important since the former is still being argued before Gonzales Ramos.

A federal appeals court last year already ruled on effect, deciding that the Texas law discriminated against minorities and the poor and ordering changes ahead of the November election. The U.S. Supreme Court last month declined a Texas appeal that sought to restore the law, but Chief Justice John Roberts hinted that the high court could eventually hear an appeal at a later time.

That appeal likely can’t happen until Gonzales Ramos rules on the Legislature’s intent, though, and she’s not expected to decide until weeks after today’s hearing.