Arizona Gov. Jan Brewer is raising money off an influx of undocumented immigrants (AP Photo/Ross D. Franklin)

Arizona officials are threatening legal action to stop the Obama administration from moving hundreds of undocumented immigrants from Texas to their state after a surge of illegal border crossings swamped immigration officials in the Rio Grande Valley.

The U.S. Border Patrol has acknowledged flying hundreds of migrants from Texas to Tucson and Phoenix, where many have been dropped off at Greyhound bus stations. Last week, immigration agencies began sending hundreds of undocumented minors apprehended while crossing the border to a holding facility in Nogales.

Arizona officials say they were not notified before the transports began.

In a letter to the Department of Homeland Security, Arizona Attorney General Tom Horne (R) insisted the department’s border security units stop the transports.

“These aliens are not being transported for the purposes of detaining them in a federal facility located in Arizona. Rather, DHS is inexplicably moving them some 1200 miles and simply releasing them here (outdoors in temperatures exceeding 100 degrees) rather than in Texas,” Horne wrote [pdf].

Arizona state law prevents Horne from bringing suit against the federal government directly, but he could find someone else to sue.

Critics of the facilities where minors are held, ranging from Sen. John McCain (R-Ariz.) to the American Civil Liberties Union, have demanded access to assess conditions they say are substandard. McCain on Thursday called for Customs and Porter Patrol to allow media access to the Nogales Processing Center.

“There is only one way of knowing what the treatment is and that’s for the media to allowed access,” McCain said Thursday on an Arizona radio show. “We need you and any media outlet that wants to be there to be there. What kind of society are we in?”

In a letter to Customs and Border Protection Commissioner Gil Kerlikowske, McCain and Sen. Jeff Flake (R-Ariz.) called the situation a “humanitarian crisis.” McCain and Flake also asked for a hearing before the Senate Homeland Security and Government Affairs Committee.

The influx of immigrants is heating up a years-old debate within Arizona political circles. Horne faces a strong Republican challenger after allegations he broke campaign finance law, and acting tough on immigration is a certain vote-getter in GOP primaries. Arizona Gov. Jan Brewer (R) is using the crisis to raise money for her federal political action committee.

The Border Patrol and Immigration and Customs Enforcement have reported a dramatic spike in the number of people caught crossing the border illegally. In January, just 28,000 people attempted to cross the border; that number spiked to 60,000 in May, according to McCain’s office.