HOLDEN — Republican U.S. Senate candidate and Maine Secretary of State Charlie Summers secured a big endorsement Thursday when the president of the National Rifle Association said the pro gun group with thousands of Maine members is behind his campaign.

NRA President David Keene was expected to announce the endorsement during a campaign rally at a military supply store focusing on 2nd Amendment rights and sportsmen’s issues.

“Traveling across Maine, sportsmen and gun owners from Kittery to Fort Kent have lent their support and rallied behind our simple, clear message of more freedom and less government,” Keene said in a prepared statement.

The NRA, the largest gun rights advocacy group in the U.S., has about four million members in the U.S.

“Unlike his opponent, Charlie Summers values the right to self-defense of the people of Maine and honors their rich hunting heritage,” Keene said.

Summers is running against former Maine governor and independent candidate Angus King, state senator and Democratic candidate Cynthia Dill and independents Andrew Ian Dodge, Steve Woods and Danny Dalton.