Major R. Owens during a hearing in Washington on Nov. 28, 1989. Owens, a former librarian, anti-poverty organizer and state senator who served 12 terms in the U.S. House of Representatives, died Oct. 21 in New York. He was 77. (James K. W. Atherton/The Washington Post)

Major R. Owens, a former librarian, antipoverty activist and New York state senator who served 12 terms in the U.S. House and became the self-styled “Rappin’ Rep” for channeling his liberal advocacy into musical verse, died Oct. 21 at a hospital in Manhattan. He was 77.

The cause was congestive heart failure, said his wife, Maria Cuprill-Owens.

Mr. Owens, a Brooklyn Democrat, was first elected to the House in 1982 and boasted of his progressive voting record at a time when passionate liberals often found themselves on the fringes of power.

He championed universal health care, education funding and minimum-wage legislation and fought to repeal gun rights, even publicly voicing his support to eliminate the Second Amendment because of the increased gun violence in schools. “I’m all alone on this one,” he once said.

It was not the first or last time he found himself without overwhelming support. Song became “an outlet for political frustrations,” he said.

He used the well of the House to criticize state and city officials for using eminent domain to transfer property from one landowner to another, at what he considered the expense of the working poor.

He opposed the massive Atlantic Yards development project in Brooklyn and rendered it this way:

Fight the pain

defeat the strain

rally all together

destroy eminent domain.

Monster on the street

grabs any home to eat

greedy rape the snakes repeat.

Having assailed U.S. involvement in the Persian Gulf War in the early 1990s, Mr. Owens went to the House floor shortly before the U.S.-led invasion of Iraq in 2003 and denounced the impending conflict:

Stop the war

We need the cash

Give Medicaid families

All of Rumsfeld’s stash

Throw the body bags

into the trash.

When not condemning conservative policy or action, Mr. Owens was sometimes an outsider within his party. After several terms in the New York Senate, he ran in 1982 to succeed the retiring Shirley Chisholm, the first black woman elected to Congress.

Chisholm and the Brooklyn Democratic Party organization backed another state senator, Vander L. Beatty, whose flamboyance and skill as a party operative made Mr. Owens appear reserved and professorial by comparison.

Despite his energetic campaign, Beatty was tainted by accusations of voter fraud and other irregularities and was subsequently convicted of those charges. He was fatally shot in 1990 while attempting a political comeback.

In Congress, Mr. Owens rose in the 1980s through the Education and Labor Committee and chaired its subcommittee on select education and civil rights. He helped shepherd the Americans With Disabilities Act of 1990, which broadened civil rights already protected in earlier legislation, as well as bills to reauthorize grants to help the disabled with job training.

With the Republican takeover of the House in 1995, Mr. Owens struggled to advance bills to protect minimum-wage increases and the Occupational Safety and Health Administration.

In 2003, Mr. Owens became one of the first members of the Congressional Black Caucus to endorse the Democratic presidential campaign of former Vermont governor Howard Dean, an internist who emphasized health-care legislation and who was a vociferous opponent of the Iraq war.

Dean, who later became chairman of the Democratic National Committee, lost the nomination to then-Sen. John F. Kerry of Massachusetts, who lost to Republican George W. Bush in the general election.

Meanwhile, Mr. Owens faced increasingly hard election challenges in his district. He was dismayed when a longtime family friend and political ally, Jamaican-born City Council member Una Clarke, campaigned for his House seat in 2000 and accused him of not keeping up with “the needs of the changing community.”

Mr. Owens accused her of using her ethnicity as a wedge issue in a district where African Americans and Caribbean Americans sometimes tussled for political visibility. He later referred to her House bid — and that of her daughter, City Council member Yvette D. Clarke, in 2004 and 2006 — as a “long-term double-cross and stab in the back.”

Mr. Owens declined to seek reelection in 2006. He was succeeded by Yvette Clarke (D), who crushed Mr. Owens’s son Chris in the race. Major Owens helped set a divisive tone during the race when he called City Council member David Yassky, who is white, a “colonizer” for his attempt to seek the House seat held for two generations by black politicians.

Major Robert Odell Owens was born in Collierville, Tenn., on June 28, 1936, and raised in nearby Memphis. His father was a laborer in a furniture factory.

Mr. Owens was a 1956 graduate of Morehouse College in Atlanta and received a master’s degree in library science from Atlanta University (now Clark Atlanta) in 1957.

He settled in Brooklyn, where he became a librarian and grew active in the Congress of Racial Equality and community development groups. Mayor John V. Lindsay tapped Mr. Owens as commissioner of the city’s antipoverty Community Development Agency in 1968. He spent five years in that job and also won election to the state Senate in 1974.

His first marriage, to the former Ethel Werfel, ended in divorce. Besides his wife of 25 years, survivors include three sons from his first marriage, Chris Owens and Millard Owens, both of Brooklyn, and Geoffrey Owens, an actor who played the son-in-law Elvin on “The Cosby Show,” of Montclair, N.J.; two stepchildren, Carlos Cuprill of Spotsylvania, Va., and Cecilia Cuprill-Nunez of Washington; three brothers; a sister; and eight grandchildren.

When he retired from Congress, Mr. Owens declared, “I want to spend my last years writing novels and poetry.” His book, “The Peacock Elite: a Subjective Case Study of the Congressional Black Caucus and Its Impact on National Politics,” was published in 2011. He was also writing a novel called “Taliban in Harlem,” about terrorists.