SAN FRANCISCO -- Arizona's immigration law faced tough scrutiny from a federal appeals panel Monday as the state's governor appeared in person to support the controversial provision on the day before the election in which she's seeking her first full term.

The 9th U.S. Circuit Court of Appeals signaled it was ready to toss out the provision of Arizona's law that criminalizes the failure to carry immigration papers showing lawful residency in the United States.

But the three-judge panel didn't tip its hand over which way it was leaning on other provisions of the state law that touched off a national furor when Arizona Gov. Jan Brewer signed it April 23. The federal government filed a lawsuit soon after to invalidate the measure.

U.S. Deputy Solicitor General Edwin Kneedler argued Monday that the provisions in question violate laws making immigration enforcement the exclusive domain of the federal government.

Among the provisions at issue is the requirement that police -- when enforcing other laws -- must question the immigration status of people they have reason to suspect are in the country illegally.

"It's how the state wants to use its people," said Judge Carlos Bea, appointed to the bench by President George W. Bush. "The state can turn over an illegal to federal officials."

Kneedler responded that requiring local law enforcement officials to check the immigration status of everyone they suspect as being an illegal immigrant takes away from their investigatory discretion. He also said the law intrudes upents of the law in this politically liberal city outnumbered supporters.

Afterward, Arizona's governor said she intended to appeal any adverse ruling to the U.S. Supreme Court. Illegal immigrants are overwhelming Arizona's health care systems, schools and prisons, she said.

The law and the federal lawsuit to overturn it have breathed new life into Brewer's re-election campaign against Democrat Terry Goddard, the state's attorney general. Brewer, a Republican, took office in January 2009 when Janet Napolitano became Homeland Security secretary.

Brewer said the Obama administration's lawsuit was misguided because the state law seeks only to address a growing problem in Arizona.

"We are not the enemy -- we are part of the United States," she said. "We need more help and support."