BANGOR, Maine — Investing in early childhood education pays off with more high school graduates and more people prepared to join the military, said three retired generals from Maine who gathered Tuesday to urge support of the president’s plan to provide preschool to the nation’s needy children.

Retired U.S. Army Maj. Gen. Earl Adams, retired Air Force Brig. Gen. Ralph Leonard and retired Army Brig. Gen. Robert Carmichael gathered at Downeast Elementary School to first read books to Kathryn Griffith’s pre-kindergarten class of 4- and 5-year-olds.

Afterward, the retired generals, who are part of a nonpartisan group called Mission: Readiness, spoke about a newly released study, “ A Commitment to Pre-K is a Commitment to National Security,” which estimates 75 percent of those age 17 to 24 in the United States are unable to join the military because they are too poorly educated, are overweight or have serious criminal records.

“It’s a rather alarming statistic,” Adams said. “The [most concerning] one is the lack of education.”

He went on to say that, “In Maine, 16 percent of our high school students don’t graduate on time” and of those who do graduate, “19 percent of them cannot pass the test to get in [the military]. This is not a very hard test.”

The national report from 2011 showed that 22 percent of high school students didn’t graduate on time.

Leonard, who graduated from Old Town High School, went to West Point and is now an aide to the secretary to the Army representing Maine, said he first heard about the education problem from recruiters.

“Our recruiters were complaining [that those who applied to join the military] couldn’t meet the minimum standards,” Leonard said.

President Barack Obama introduced his preschool education plan at the State of the Union address in February and again in April when he unveiled the Preschool for All plan as part of his 2014 proposed budget, which includes investing $75 billion over a 10-year period to provide preschool for all 4-year-olds near or below the federal poverty line.

Families that earn up to 200 percent of the federal poverty level would qualify for the Preschool for All program, Leonard said. A family of four can make up to $47,100 and still qualify, according to the 2013 federal poverty guidelines.

“Families that are struggling” are the ones who cannot afford to enroll their children into preschool programs, which can cost thousands of dollars over a year’s time, Leonard said.

The good news is that “Maine recognized the problem,” he said, and in 2001 began to make preschool investments statewide.

The president’s plan is a “state and federal partnership” to provide early education to needy 4-year-olds, Carmichael said.

The Preschool for All program is a 10-year investment that is designed to provide competitive grants to help states add early education programs and to create partnerships with established programs such as Head Start, the Mission: Readiness report states.

Under Obama’s proposal, Maine would receive an estimated $5.5 million in the first year of the program, which would need to be matched by $500,000 from the state.

Kim Gore, Mission: Readiness state director and state director for America’s Edge, a nonprofit group that advocates for early childhood education, said the county has a “historic investment opportunity” with the White House plan.

“We support smart investments in our children, particularly in education,” she said.

Mission: Readiness is a nonpartisan national security organization of 350 retired admirals and generals, including 27 in Maine, who are calling for smart investments in America’s children. It and America’s Edge both fall under the umbrella of the nonprofit Council for a Strong America.

Bangor Superintendent Betsy Webb ended the press conference by saying the School Department was one of the first to jump on board in support of a pre-kindergarten program.

A pilot pre-kindergarten program was started during the 2004-05 school year and has grown by leaps and bounds over the years.

“We serve 75 percent of the students who are eligible,” Webb said, adding there are pre-kindergarten programs in all of the Queen City’s elementary schools. “We’re able to serve any student who wants a program.”

Those who enrolled in the 2004-05 pilot pre-K program showed marked improvements in literature and math that carried forward as they entered middle school, and those who were identified as “at risk … were able to close the gap,” Bangor’s superintendent said.

The pilot class is scheduled to graduate in 2016.

“We look forward to monitoring their progress,” Webb said.