An illegal immigrant leans on a plaque marking the U.S. boundary with Mexico at Las Margaritas border crossing in Nogales, Ariz., on Monday. ((Alonso Castillo/Reuters))

A U.S. judge has blocked the most controversial sections of Arizona's new immigration law from taking effect Thursday, handing a major legal victory to opponents of the crackdown against illegal migrants.

The law is still to take effect — but without many of the provisions that angered opponents, including sections that required police officers to check a person's immigration status while enforcing other laws.

Republican Gov. Jan Brewer said the state likely will appeal the ruling and try to get the judge's order overturned.

"It's a temporary bump in the road," she said.

On Wednesday, U.S. District Judge Susan Bolton also put on hold parts of the law that would require immigrants to carry their identification papers at all times and make it illegal for undocumented workers to solicit employment in public places.

Bolton put those controversial sections on hold until the courts resolve the issues.

The ruling came as police made last-minute preparations to begin enforcing the law at 12:01 a.m. MT, and opponents planned large demonstrations against it.

At least one group planned to block access to federal offices, daring officers to verify their immigration status.

The volume of the protests will likely be turned down a few notches because of the ruling.