(Adds comments from Reverend Jesse Jackson, Texas state Senator Rodney Ellis)
By Steve Holland and Karen Brooks
AUSTIN, Texas, April 10 (Reuters) - Barack Obama on Thursday praised the civil rights legacy of former President Lyndon B. Johnson, saying his 1960s pursuit of equality helped clear the way for an African-American to one day become U.S. president.
Obama was joined by three former presidents this week in commemorating the 50th anniversary of the passage of the Civil Rights Act of 1964, the landmark legislation that tested Johnson's vaunted negotiating skills and took a step toward ending America's segregationist past.
Speaking to a crowd at the Lyndon Baines Johnson Presidential Library, Obama lauded the 36th U.S. president's civil rights push as "one giant man's remarkable efforts to make real the promise of our founding: 'We hold these truths to be self-evident, that all men are created equal'."
Obama, who has so far spent much of his second term as president tussling with Republican opponents, said Johnson's "Great Society" programs aimed at providing a social safety net for low-income Americans are as vital as ever and that politicians who want to dismantle them are cynical.
"I reject such cynicism because I have lived out the promise of LBJ's efforts," he said.
Johnson opened doors of opportunity for people like him to advance in the United States, Obama said.
"They swung open for you and they swung open for me, and that's why I'm standing here today," he said, adding: "That means we've got a debt to pay."
Obama's own civil rights legacy is seen in his efforts to try to end discriminatory practices against gays and lesbians and persuading Congress to pass immigration reform. African-American groups would like him to do more to create jobs for the black community.
His audience included Johnson's daughter Lynda, some veterans of the Johnson administration and civil rights leaders, such as Representative John Lewis, a Georgia Democrat who as a young man was beaten by Alabama state troopers and his skull fractured during the "Bloody Sunday" march in March 1965.
Lewis said it was fitting that Obama spoke.
"President Barack Obama was born into a dangerous and difficult time in American history, a time when people were arrested and taken to jail just for sitting beside each other on a bus," he told the crowd.
Obama also knows there is much more work to do "redeem the soul of America," said Lewis.
'WE SHALL OVERCOME'
In remarks after Obama's speech, Reverend Jesse Jackson said Obama envisions a country that champions mutual respect and working together to solve its issues.
"He speaks for an America that's inclusive," Jackson said.
A prominent black Texas state senator said he would like to see the same Civil Rights-era activism today in support of Obama's programs, such as affordable healthcare and equal pay.
"There's a tremendous corollary between the focus on inequality of the Johnson era and the focus on inequality now," said Texas state Senator Rodney Ellis, a Houston Democrat who has helped pass anti-discrimination laws in the state.
"But it seems that we have lost our commitment to help our fellow human beings. President Johnson benefited from a strong civil rights advocacy community. At some point, the American people are going to have to speak up."
The gathering was treated to protest songs from the 1960s and videos of Johnson signing the law that outlawed discrimination based on race. In one, he is seen repeating the civil rights anthem of the time, "We shall overcome."
Gospel singer Mavis Staples later led the crowd to rise to its feet and sing "We Shall Overcome," swaying to the music.
Former presidents Jimmy Carter, Bill Clinton and George W. Bush participated, appearing at different times, but the central speaker of the week of ceremonies was Obama.
The 44th president has in recent months intensified his focus on improving the plight of black Americans. His "My Brothers Keeper" initiative is aimed at help at-risk young people to get the skills needed to find a job.
However, Obama's policy of deporting undocumented immigrants drew a protest outside the library where a half dozen people spent the night chained to a statue on the University of Texas campus.
One of those chained was Patrick Fierro, 36, of Austin, who saw his father deported to Ciudad Juarez, Mexico, six years ago and said he and his family have struggled with grief ever since.
"Every day I suffer and I have pain every day when I wake up. I miss my dad and can't see him," Fierro said, as hundreds more protesters chanted and marched before Obama's speech. (Additional reporting by Jeff Mason and Roberta Rampton in Washington; editing by G Crosse and Cynthia Osterman)