Daniel Sonenberg came a little closer this week to his dream of staging an opera based on the life of Negro Leagues baseball legend Josh Gibson, after getting a $15,000 grant from the National Endowment for the Arts.

The grant will go toward the $50,000 or more needed to stage the first concert performance of his opera “The Summer King,” on May 8 at Portland’s Merrill Auditorium. The performance was already scheduled and would have happened even without the grant, but now Sonenberg has less money to raise and can concentrate on other chores, such as finding the right singers and trying to get investors interested in staging a full production.

“The NEA grant was a very critical piece. Without it, I would have had to do a lot more fundraising in the next few months,” said Sonenberg, 43, resident composer and associate professor of music at the University of Southern Maine in Gorham. “Or we might have had to scale back the performance somewhat.”

Sonenberg has been working on his baseball opera for 10 years. Over the past few years, songs from it have been performed in public around Maine and the country, and local publications have written about it.

The whole opera, including 11 scenes and more than two hours of music, will be performed for the first time in May at Merrill Auditorium. It will be a concert performance, meaning the songs will be sung but there will be no staging, costumes or props.

Some of the opera’s songs will be sung at an opera organization convention in New York City in January. Sonenberg hopes that convention will attract people who might be interested in putting on a full-scale performance of his opera. He hopes some of those people might see the performance in Portland in May. That performance will be a collaboration with the Portland arts presenter Portland Ovations.

Sonenberg, who grew up a New York Yankees fan on Long Island, N.Y., has long been interested in baseball history and its stories. The story of Gibson is an especially tragic one.

Regarded as one of the greatest players in baseball’s Negro Leagues in the 1930s and ’40s, he wanted badly to play in the Major Leagues. But he died in 1947, the year the majors were finally integrated.

“The Summer King” will likely attract people who don’t go to traditional operas. It’s in English, and features real-life characters such as Gibson and Brooklyn Dodgers general manager Branch Rickey. The songs feature elements of the musical styles of Gibson’s time, such as jazz.

“There’s jazz, stride piano, and at one point a mariachi band on stage,” said Sonenberg. “But my goal was to weave them into a musical language that was mine.”

For more information on the opera, go to www.danielsonenberg.org.