CONCORD, N.H. — Gov. John Lynch is drafting a letter to ask federal authorities to delay enforcing the Real ID law on New Hampshire residents so they don’t encounter problems boarding airplanes and entering federal buildings starting in May.

The delay would be until Jan. 1, 2010.

If a delay isn’t granted, New Hampshire driver’s licenses not meeting a federal standard won’t be accepted as identification at airports or to enter federal buildings starting May 11, according to Sen. Judd Gregg’s office. Residents will be required to submit to a secondary screening at airports unless they have a passport or other federally approved form of identification, such as a military ID.

New Hampshire is one of only five states that have not submitted a request for a delay. Delaware, Maine, Montana and South Carolina are the other states. Gregg’s office said all requests will be granted and the extension won’t commit the state to complying with the Real ID program.

The Department of Homeland Security estimates the average cost to comply with Real ID licensing standards will be $8 for a four-year license.

‘‘We intend on asking the federal government to not begin imposing the requirements of Real ID on New Hampshire given that the state has taken a strong stand by passing a law prohibiting our participation,’’ Lynch spokesman Colin Manning said Thursday.

‘‘Gov. Lynch believes strongly the federal government needs to go back and look at the law and address privacy and cost before he would even consider allowing New Hampshire to participate,’’ Manning said.

Also Thursday, the state Senate voted unanimously to ask for an extension from the compliance deadline for the program. The Senate voted to ask Lynch to apply for the extension. The Senate said the request would not constitute participation in Real ID, which would violate state law.

Lawmakers passed a law last year barring the state from complying with the federal law, which sets standards for state-issued driver’s licenses.

The law requires all states to bring their driver’s licenses under a national standard and to link their record-keeping systems. States must verify identification used to obtain a driver’s license, such as birth certificates, Social Security numbers and passports.

The House next considers the bill, which may be moot if Lynch submits his letter by a March 31 deadline.

Gregg’s office noted that states that wish to comply with Real ID have until March 7 to apply for $83 million in grants. In 2005, Gregg had secured a $3 million grant for New Hampshire to test the law. The grant award was rescinded when New Hampshire decided against complying, his office said.