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By Ashley Killough, CNN

(CNN) — At the commemoration of the historic Selma to Montgomery civil rights march, Vice President Joe Biden on Sunday expressed guilt for not joining the Alabama demonstration nearly half a century ago.

The vice president also used the opportunity to lament the dozens of voting restrictions proposed by states in the last couple of years and argued against a challenge to the Voting Rights Act of 1965 that’s now being heard in the Supreme Court.

In his speech, Biden said he watched the first bloody march as a senior in college. The scene, he said, gave him heavy convictions.

“I regret – and although it’s not a part of what I’m supposed to say – I apologize it took me 48 years to get here,” Biden said, shortly before joining a crowd to walk across the Edmund Pettus Bridge. “I should have been here. It’s one of the regrets that I have and many in my generation have.”

The vice president, alongside notable civil rights activists such as Rep. John Lewis, led the crowd of thousands across the same bridge where police met protestors with brutal force nearly 50 years ago.

“Most of us thought that the hatred the viciousness the bigotry that we’d seen in our own states had at least subsided,” Biden said, reflecting on watching the protests. “What we saw was entrenched hostility and prejudice coming face to face with undaunted courage and resolve – a resolve so powerful that it inspired the Congress and the nation to support the Voting Rights Act just four months later.”

Biden was elected to the Senate just seven years out of college at the age of 29. Leading up to his first run, he said, “nothing shaped my consciousness (more)…than what happened here in Selma.”

This appearance was Biden’s first at the tribute. President Barack Obama and former Secretary of State Hillary Clinton came to Selma in 2007 when they were both seeking the Democratic presidential nomination. Biden, himself, has not ruled out a 2016 presidential bid.

While Obama did not accompany Biden on Sunday, the president made headlines when he mentioned Selma and other landmark events in the civil rights movement during his second inauguration speech in January.

“We, the people, declare today that the most evident of truths – that all of us are created equal – is the star that guides us still; just as it guided our forebears through Seneca Falls, and Selma, and Stonewall,” he said.

On March 7, 1965, police clashed with nearly 600 marchers in Selma, forcing them back from the Edmund Pettus Bridge with batons and tear gas. On a day that later became known as “Bloody Sunday,” police said they were enforcing then-Gov. George Wallace’s ban on demonstrations.

Carrying on the march, the demonstrators ultimately made it to the state’s capital, Montgomery, on March 24. The vice president applauded those who took part in the demonstrations, saying they helped “liberate the soul of the United States of America.”

“You lost the battle that day, but you won the war,” he told the audience at the foot of the bridge. “And in the process you did something that could never be changed: you won the hearts and minds of your fellow citizens all across America.”

In a separate speech earlier in the day, Biden added the fight still continues in 2013, pointing to a series of voting laws proposed during the 2012 election and warning of the current case at the Supreme Court involving the Voting Rights Act of 1965.

The court will decide this year on challenges to Section 5, a part of the act that gives the federal government open-ended oversight of states and localities, mostly in the South, with a history of voter discrimination. As the law now stands, changes in voting laws and procedures in all or parts of 16 covered states must be “pre-cleared” with Washington.

Conservative justices on Wednesday suggested it was a constitutionally unnecessary vestige of the civil rights era. The provision was reauthorized by Congress in 2006 for another 25 years and officials in Shelby County, Alabama, subsequently filed suit, saying the monitoring was overly burdensome and unwarranted.

But advocates for the provision say it’s necessary to protect voting rights. Biden on Sunday lambasted the idea that Section 5 was even up for debate.

“Strom Thurmond voted for its reauthorization, and yet it’s being challenged in Supreme Court of United States of America as we stand here today,” Biden said.

The vice president also highlighted other states’ attempts to pass voter identification laws last year during the election. According to the National Conference of State Legislatures, 32 states have some sort of voter identification law. Those states include Georgia, Mississippi, South Carolina and Texas, places that also must get Voting Rights Act clearance before enacting new laws.

Democrats have said that such laws are politically motivated and intended to suppress the minority vote, given that fewer people in minority groups carry government-issued IDs. Republicans, meanwhile, make the case that such laws prevent fraud and protect the integrity of the system.

Biden acknowledged that Americans have changed during the last five decades but emphasized “we’ve come too far together to turn back.” And in closing his remarks earlier Sunday, the vice president reiterated his regret of not traveling to walk in solidarity with the demonstrators in 1965.

“I still feel just a little bit of guilt; I was old enough,” he said. “I could have been here. I should have been here, 48 years ago.”

CNN’s Bill Mears contributed to this report.