Bernie Sanders, whose ability to connect with black voters remains a barrier to his White House bid, pledged Monday during a large-scale rally in Birmingham, Ala., that his agenda would build upon the vision of civil rights icon Martin Luther King Jr.

Speaking on the national holiday commemorating King’s legacy, the Vermont senator told an overflow crowd estimated at more than 7,000 people that King’s work, in addition to civil rights, focused on helping poor people, regardless of race.

Sanders reminded the audience that King was assassinated in 1968 in Memphis, where he had traveled to show solidarity with striking city sanitation workers.

“The fight for economic justice is exactly what this campaign is about,” Sanders said, vowing to fight to carry on King’s “radical and bold vision for America.”

“It is absolutely imperative that we see his life not as a museum piece … to be kept on a shelf,” said Sanders, a self-described democratic socialist, during a rally that was live streamed over the Internet.

In his race for the Democratic nomination against Hillary Clinton, Sanders has pulled close to her even in Iowa and led in recent polls from New Hampshire, two states with largely white populations. But Clinton remains a heavy favorite among African American voters, a key constituency in states that follow, who are far more familiar with her and her husband, former president Bill Clinton.

Alabama is among 11 states with primaries or caucuses scheduled on March 1, a potentially pivotal day in the nomination fight known as Super Tuesday.

Sanders, 74,opened his remarks in Birmingham -- a city important to King’s legacy -- by sharing that he was present in August 1963 when King delivered his “I Have a Dream” speech in Washington.

“I was there at the March on Washington, and I can remember the day in my mind’s eye,” Sanders said. He called it a day that “left a lasting impression.”

Sanders also referenced one of King’s famous lines about the intersection of racial and economic justice --  “What good is having the right to sit at a lunch counter if you can’t afford to buy a hamburger?” -- as he talked about some of his own proposals.

Sanders, for example, has called for making college tuition-free at public colleges and universities.

“What does it mean if you can go to a university but you can’t afford to go to the university?” he asked his crowd in Birmingham.

Earlier during his trip to Birmingham, Sanders toured a Baptist church where King had preached that was bombed and visited the Civil Rights Institute, a museum in the city, where Sanders touched the bars of the cell where King was jailed, according to a report filed on the visit by the Birmingham News.

Sanders’s evening rally was his first since Sunday night’s Democratic debate in South Carolina with Clinton and former Maryland governor Martin O’Malley, and Sanders appeared more energized than usual.

“There must be some kind of mistake,” he said upon greeting the large crowd, some of whom watched him on a jumbo TV outside the auditorium. “I was told Alabama was a conservative state.”

Referring to recent polls showing competitive contests with Clinton in Iowa and New Hampshire, Sanders said that “that inevitable candidate ain’t so inevitable today.”

Earlier Monday, Sanders appeared at another event commemorating King, in Columbia, S.C., where he shared the stage with both Clinton and O’Malley.

Sanders is scheduled to return to Iowa on Tuesday for a daylong campaign swing.