The president calls the state's tough legislation a wake-up call for the federal government to overhaul the nation's immigration system. White House officials fear a patchwork of state laws that don't resolve border issues or deal with the 11 million people in the U.S. illegally.

A tough new Arizona law aimed at rooting out illegal immigrants is reshaping the arguments used by the Obama administration and congressional Democrats in support of a sweeping overhaul of the nation's immigration system.

White House officials say the Arizona law underscores an untenable void in federal immigration policy. Without congressional action, they warn, Arizona and other states will create a patchwork of laws that don't resolve the core problem: how to strengthen the borders and deal with the 11 million people who are in the U.S. illegally.

"The president has said … that this is a wake-up call for the federal government to act," said White House Press Secretary Robert Gibbs.

Speaking on the Senate floor, Sen. John McCain (R-Ariz.) defended the law. At one time, McCain was a voice for broad-based immigration changes. Now, challenged in his Senate reelection bid by a conservative primary opponent, McCain is taking a hard-line stance on immigration, focusing more on border security than on finding a path to legal status for undocumented immigrants.

McCain goes from wetback appeaser to "hardliner" overnight. Got to love those mid-term elections.