Arizona's new immigration law will go into effect Thursday without its key parts.

A federal judge has put the most controversial sections of the law on hold until the courts resolve the issues, in what could be a long legal battle.

Gov. Jan Brewer calls today's ruling by U.S. District Judge Susan Bolton "a temporary bump in the road," and says she expects to appeal.

Arizona Attorney General Terry Goddard, a Democrat who's running against Brewer, says the Republican governor "played politics with immigration, and she lost."

The judge shelved parts of the law requiring immigrants to carry their papers at all times and police to check immigration status while enforcing other laws. And she blocked officers from making warrantless arrests of suspected illegal immigrants.

Also on hold is a ban on undocumented workers soliciting employment in public places.

In Mexico City, word of the ruling was greeted with cheers from about 100 protesters who had gathered in front of the U.S. Embassy.

The U.S. Justice Department says the judge ruled correctly.

Department spokeswoman Hannah August said Wednesday that the department understands the frustration of Arizona residents with the immigration system.

August added that a patchwork of state and local policies would seriously disrupt federal immigration enforcement.

©2010 The Associated Press. All rights reserved.