* Lawsuit comes days after Obama pushes immigration reform
* State has defended law as necessary to deal with crime
WASHINGTON, July 6 (Reuters) - The Obama administration is expected to sue the state of Arizona as early as Tuesday over its new, strict immigration law, two administration officials familiar with the plans said.
The controversial law, which goes into effect on July 29, requires state and local police to investigate the immigration status of anyone they reasonably suspect of being an illegal immigrant, provoking criticism that it is unconstitutional.
The Republican-controlled Arizona legislature passed the law to try to stem the flood of thousands of illegal immigrants who cross its border from Mexico each month and to cut down on drug trafficking and other crimes in the area.
The lawsuit is part of a broader approach by President Barack Obama to deal with the 10.8 million illegal immigrants believed to be in the country. Last week, he called for Republicans to work with him on a federal law to further stem the flood of illegal crossings into the United States.
The legal fight also comes at a critical juncture, four months ahead of the mid-term congressional elections and the Hispanic community has been a major voting bloc that typically has sided with Democrats but Republicans have tried to woo.
The officials said the lawsuit was expected later on Tuesday but declined to give further details.
A Justice Department spokeswoman declined to comment.
Administration officials and critics have condemned the law, raising questions about whether it was constitutional and could lead to racial profiling and broaden a rift with Hispanics, a rapidly growing population in the United States.
President Barack Obama has warned that the Arizona law could lead to a patchwork of different laws passed by the various U.S. states and said that the matter should be resolved at the federal level by Congress.
Last week he gave his first major speech on immigration reform since taking office, calling for both political sides to join together to pass a comprehensive measure, but it has largely been overshadowed by the economic crisis and the oil spill in the Gulf of Mexico.
“Reform that brings accountability to our immigration system cannot pass without Republican votes. That is the political and mathematical reality,” Obama said.
Obama has backed allowing undocumented immigrants in good standing to pay a fine, learn English and become citizens. He also has supported tightening border security and clamping down on employers that hire undocumented workers.
But opposing Republicans have said that border security must be significantly improved before dealing with the millions of illegal immigrants, many of them Hispanics, in the country.
Mexico and several civil liberties groups have opposed the Arizona measure, and several other legal challenges are pending in federal court in the state.
Obama has pledged to spend an extra $600 million and send up to 1,200 National Guard troops to the U.S.-Mexican border to tighten security, however the initial steps to do so have been criticized as too little to address the problem.
Reporting by James Vicini and Jeremy Pelofsky, Editing by Sandra Maler