WASHINGTON — John Sweeney, who spent 14 years steering the AFL-CIO through a time of declining union membership and rising internal dissent, has died. He was 86.

He died on Monday at his home in Bethesda, Maryland, AFL-CIO national media manager Carolyn Bobb said. The cause of his death wasn’t disclosed.

Sweeney was credited with transforming the nation’s largest labor federation into a political powerhouse more firmly aligned with the Democratic Party, as well as with civil rights, environmental and anti-poverty groups.