But the 2016 Committee, the “super PAC” that worked to nudge Mr. Carson into running for president, is not promoting Donald J. Trump, the presumptive Republican nominee, at least not directly. “The 2016 Committee is committed to defeating Hillary,” Mr. Sousa said, and it is planning to run commercials on black radio stations in nine swing states. He said that he had employed a similar strategy to help conservative candidates in North Carolina and Louisiana in 2014, with the goal of helping Republicans take control of the Senate, which he hoped would persuade Mr. Carson to run for president. This year he had a $4 million budget in mind. “If we can take the black vote away from Hillary,” Mr. Sousa said, “then Hillary will lose.”

After the November election, he has planned another focus for the 2016 Committee, including a name change. It will become the Stars and Stripes Forever Super PAC, he said.

“What that is going to do is identify conservative minorities to run for Senate seats,” he said. “If the Republican Party doesn’t become more inclusive, and if the Republican Party doesn’t get more minorities involved at senior levels of government, it will be over for the Republican Party.” He paused, then said, “It may be over anyway.”

In person, sitting on the patio behind his townhouse in this central Connecticut town, Mr. Sousa was polite. He is less so on Facebook, where, between posts about his great-grandfather and his own efforts to promote Sousa’s music and bands that play it, he has attacked President Obama and Hillary Clinton.

After the massacre in a gay nightclub in Orlando, Fla., he put the blame for the shooting on the president. Mr. Sousa wrote, using an adjective that cannot be printed here, that Mr. Obama’s way of “dealing with Muslim terrorists, with immigration, with political correctness resulted in this dreadful tragedy.”