McALLEN, Texas — Plans by Texas to arrest migrants suspected of entering the U.S. illegally were again on hold Wednesday after setting off uncertainty along the border and anger from Mexico flared during a brief few hours that the law was allowed to take effect.

A late-night order Tuesday from a 5th U.S. Circuit Court of Appeals panel put on hold — again — Texas' dramatic state expansion into border enforcement. Earlier in the day, the U.S. Supreme Court had cleared the way for the strict immigration law, dealing a victory to Republican Gov. Greg Abbott and encouraging GOP lawmakers in other states that are pushing for similar measures.

But later in a 2-1 order, an appeals court panel continued the legal seesaw surrounding the Texas law, again pausing it ahead of oral arguments that were scheduled for Wednesday. It was not clear how quickly the next decision might come.

During the short time the law was in effect Tuesday, Texas authorities did not announce any arrests or say whether it was being actively enforced. Along the border in Kinney County, Sheriff Brad Coe embraced the arrest powers but said deputies would need probable cause.

“It is unlikely that observers will see an overnight change,” said Coe, whose county covers a stretch of border near Del Rio that until recently had been the busiest corridor for illegal crossings but has quieted considerably.

The Supreme Court did not rule on the merits of the law. It instead kicked back to the lower appeals court a challenge led by the Justice Department, which has argued that Texas is overstepping the federal government's authority.

The latest appeals court order included no explanation from the panel. But it had the effect of restoring an injunction issued in February by U.S. District Judge David Ezra, who rebuked the law on multiple fronts. His 114-page opinion brushed off Republicans' claims of an “invasion” along the southern border due to record-high illegal crossings. Ezra, an appointee of former President Ronald Reagan, also warned that the law could hamper U.S. foreign relations.

Under the Texas law, once defendants are in custody on illegal entry charges, they can agree to a judge's order to leave the U.S. or face prosecution. On Tuesday, Mexico’s Foreign Affairs Secretary said in a sharply worded statement that it would refuse to take anyone back who is ordered to cross the border.

“Mexico reiterates the legitimate right to protect the rights of its nationals in the United States and to determine its own policies regarding entry into its territory,” the government said.

The impact extends far beyond the Texas border. Republican legislators wrote the law so that it applies in all of the state’s 254 counties, although Steve McCraw, the director of the Texas Department of Public Safety, has said he expects it will mostly be enforced near the border.

Other GOP-led states are already looking to follow Texas’ path. In Iowa, the state House gave final approval Tuesday to a bill that would also give its state law enforcement the power to arrest people who are in the U.S. illegally and have previously been denied entry into the country.

It now goes to Republican Gov. Kim Reynolds. If signed, it would take effect in July.

“The federal government has abdicated its responsibilities and states can and must act,” Republican Iowa state Rep. Steven Holt said.

In Texas, El Paso County Judge Ricardo Samaniego, the top county executive, said immigration enforcement should remain a federal, not state, responsibility, echoing the Biden administration's view. He said heightened law enforcement presence in the city of El Paso during a previous migrant surge brought high-speed chases and traffic stops based on assumptions that passengers were in the country illegally.

“We had accidents, we had injuries, we got a little glimpse of what would happen if the state begins to control what happens in respect to immigration,” Samaniego said.

Skylor Hearn, executive director of the Sheriffs’ Association of Texas, said sheriffs' offices have been training since last year.

“If a county chooses to take it on themselves, they are choosing for their taxpayers to take it on themselves as well,” Hearn said. “As long as the federal government is willing to do its part that it is supposed to be doing, it is ideal for them to take possession and custody of these people."

Daniel Morales, an associate professor of law at the University of Houston Law Center, said the Texas law "will be a mess, very clearly, to enforce.”

“It’s very clear that Greg Abbott wants to enforce the law so he can get lots of photo ops and opportunities, but it’s gonna take a lot of state resources to implement. And I don’t know, in fact, how much appetite and capacity for that the state government actually has,” Morales said. Texas will find enforcement is “difficult and taxing,” he said.

Arrests for illegal crossings fell by half in January from a record-high of 250,000 in December, with sharp declines in Texas. Arrests in the Border Patrol's Del Rio sector, the focus of Abbott's enforcement, fell 76% from December. Rio Grande Valley, the busiest corridor for illegal crossings for much of the past decade, recorded its fewest arrests since June 2020.

Tucson, Arizona, has been the busiest corridor in recent months, followed by San Diego in January, but reasons for sudden shifts are often complicated and are dictated by smuggling organizations.

When President Joe Biden visited the Rio Grande Valley for his second trip to the border as president last month, administration officials credited Mexico for heightened enforcement on that part of the border for the drop in arrests. They said conditions were more challenging for Mexican law enforcement in Sonora, the state that lies south of Arizona.