Four years ago, the NRA endorsed Democrat R. Creigh Deeds over McDonnell in their race for attorney general. There was no immediate comment on Monday's endorsement from Deeds' campaign.
"The Second Amendment rights of law abiding Virginians must be respected and protected," McDonnell said. "That is what I did while serving as Virginia's Attorney General."
McDonnell and Deeds, an outdoorsman who represents a mountainous, rural stretch of western Virginia in the state Senate, both have legislative track records that are mostly favorable to gun rights.
Deeds opposed then-Gov. L. Douglas Wilder's successful legislation in 1993 to limit handgun purchases in Virginia to one per person per month. Virginia had gained a reputation as a major East Coast supplier of guns, many of which turned up in the hands of criminals.
McDonnell, citing the interests of law enforcement, supported the one-gun-a-month law.
"We worked to stop unauthorized attempted straw purchases by outside agents operating in the commonwealth," McDonnell said. "We moved quickly to make the commonwealth one of the first states to file an amicus brief in support of the individual right to bear arms in the historic Supreme Court Case of District of Columbia v. Heller."
Deeds sought to close a loophole in state law that exempts private firearms sellers at gun shows from conducting the same background checks that federally licensed gun dealers must perform.
His action came after the April 2007 massacre at Virginia Tech in which a student gunman with two handguns shot 32 people dead on the Blacksburg campus, then killed himself as police closed in.
McDonnell, the state attorney general from January 2006 until February, when he resigned to campaign for governor full time, opposed efforts to close the "gun show loophole."
"His opinions and actions as an attorney general have protected and enhanced the Second Amendment rights of law-abiding Virginians," said NRA-PVF Chairman and NRA Institute for Legislative Action Executive Director Chris Cox. "His zero-tolerance attitude toward criminals makes him the best choice for governor."
The NRA has more than 120,000 members in Virginia.
Deeds picked up an endorsement of his own Monday. The Virginia Professional Firefighters Association, a leading advocate for the safety and training of the commonwealth's firefighters and paramedics, is backing him. Deeds promised that he would not cut public safety funding to pay for transportation projects.