PHOENIX — Arizona residents may find themselves unable to use their state driver licenses to board aircraft as soon as May 11.

 On that day, only residents of states which have complied with the new requirements of the 2005 Real ID Act will have their driver licenses recognized by federal officials for the purpose of travel. The same will be true for using the license as proof of identity to enter most federal buildings.

 Instead they will need something else, like a passport or military ID card.

 Russ Knocke, spokesman for the U.S. Department of Homeland Security said his agency will issue waivers to states that indicate by then they eventually will comply with the new requirements but just need a little more time.

 But none of that may help Arizona. That’s because two lawmakers are pushing a measure to specifically block the state from cooperating in creating what they believe will be the equivalent of a national identification card.

 And Rep. Judy Burges, R-Skull Valley, said one version of the measure will be referred directly to voters, getting around a potential veto by Gov. Janet Napolitano. Sen. Karen Johnson, R-Mesa, who is working with Burges, called the Real ID requirements an unwarranted intrusion into privacy.

 She rejected arguments that the new licenses are necessary to protect national security. “If you want to give up your liberty for security, you’re going to end up with neither one,’’ she said.

 There is broad legislative opposition to the federal requirements.

 The state Senate voted last year to bar Arizona from participating in the Real ID program. The measure also was approved by two House committees but never got a final vote.

 It may not even take legislative action to block Arizona from requiring the new licenses.

 Gubernatorial press aide Jeanine L’Ecuyer said Friday she is unsure whether Napolitano has the power to unilaterally order the state Motor Vehicle Division to revamp its licensing procedures.

 The governor may, in fact, have to get legislative permission for the change, as well as to pass on the additional cost of $8 per license to motorists.

 Sen. Karen Johnson, R-Mesa, is working with Burges on  Knocke said states are free to ignore the new regulations. But he said legislators who object are being short-sighted. “That tells me that those lawmakers are OK with illegal aliens continuing to exploit the system we have today to be able to use the identities of American citizens to get licenses,’’ he said.

 The licenses were mandated by Congress in the wake of the Sept. 11, 2001 terrorist attacks. Several of the hijackers had multiple identifications — and multiple licenses.

 Under Real ID, states would be required to verify the identity and legal presence of driver license applicants. That includes checking against the government’s Social Security database as well as “pinging’’ the computers of the other 49 states to ensure that the person does not already have a license under a different name, perhaps by using a different initials. “This is nothing but tremendous Big Brother,’’ Johnson said. “When in the history of this country have we ever required people to have to have a card or something to move around in their own country?’’

 Neither Johnson or Burges said their objections were blunted by the fact the license would be required only for air travel. Despite the May 11 deadline, states that indicate they’re willing to comply will have until 2011 to issue new licenses to anyone born after Dec. 1, 1964. Older residents, who Knocke said are considered to be a lower risk of being terrorists, will have until 2017 to replace their existing licenses.

 If Arizona opts out, it will not be alone: the American Civil Liberties Union says lawmakers in 17 states already have approved resolutions to not participate.

 Knocke said some of these were concerns about costs. He said his agency has addressed that by altering the rules to give states more flexibility in some requirements, like what card stock to use, moves he said cut the price tag nationwide from $14.6 billion to $3.9 billion.

 The licenses also will not contain a microchip with embedded unique ID numbers as had been discussed.

 And Knocke said his agency will provide some funds to states willing to participate, though that may end up being less than a dime on every dollar. The balance, he said, will have to be picked up by the states — or by the motorists in higher license costs.

 Real ID licenses also will be good for only eight years; Arizona licenses now are good until motorists turn 65. Not all of the changes needed to comply with Real ID will cost money.

 One requires states to take the photos of applicants when they first apply rather than at the end of the process.

Knocke said that is designed to ensure that if the person’s documents prove false — and a license is not issued — that the state has a photo on file.

 Burges said if the federal government is concerned about terrorism it should spend more time and money securing the border rather than imposing new requirements on U.S. residents.

 The Real ID requirements are separate from an agreement last month by Napolitano with federal officials to create an optional license for Arizonans who want to be able to use them to enter the country without a passport.

Napolitano conceded at the time she definitely needs legislative approval for that change.