Joe Biden entered the 2020 race for president Thursday at the top of the polls, with universal name recognition and the still-fresh sheen of his time as a popular vice president to Barack Obama.

In a video posted to his social media platforms, Biden characterized the race as a “battle for the soul of this nation.”

“If we give Donald Trump eight years in the White House he will forever and fundamentally alter the character of this nation — who we are — and I cannot stand by and watch that happen,” he says in the 3½-minute video.

Biden will travel to Pittsburgh on Monday to deliver a speech about the middle class, then to Iowa the next day. He will travel through several early voting states for the next two weeks before returning to Pennsylvania to make a speech about “unifying America” in Philadelphia on May 18.

Watch: Joe Biden is running for president, here are some congressional basics 

“I don’t believe there’s any precedent for a candidate like Biden,” who cast thousands of votes on the Senate floor and in committee during his career, said Joseph Pika, a professor emeritus at the University of Delaware who has followed Biden’s career.

“All those votes can be sliced and diced by critics to prove almost anything they want — inconsistencies, errors in judgment, wrong choices,” Pika said. “And with experience in  national office spanning nearly a half century, the issues have changed and evolved, as has the expert thinking about best solutions.”

A CQ/Roll Call analysis found that during his career, Biden cast some votes against the majority of his party, but generally he was among senators who were more supportive of Democratic presidents and opposed to Republicans. Yet there are also potential potholes on the road to the nomination.

Podcast: Why a crowded ‘knife fight’ is good for DemocratsHe championed “tough-on-crime” criminal justice policies now thought to have contributed to mass incarceration, a modern civil rights issue that could be important in early voting states such as South Carolina. He cast votes that would have curtailed women’s access to abortions. And he pushed for the passage of a law that stripped bankruptcy protections from millions of Americans in 2005.

It remains to be seen how much his opponents will focus on that history during the Democratic primary campaign, which is still in its early phase. But even before he announced his candidacy, Biden was already positioning himself to respond to critics from the “New Left.”

Watch: Biden announces 2020 presidential campaign

Biden brings 40 years of political baggage that could force him to explain or apologize for dozens of past positions that are out of step with a Democratic Party that is being pulled further left.How Biden chooses to frame a Washington record that stretches back to the Nixon administration could determine the course of his candidacy.

“I’ve got the most progressive record of anyone running,” he said at a March event in Delaware. Biden’s campaign did not respond to interview requests for this story.

Biden’s supporters and some political experts have described now-controversial positions as the unavoidable legacy of a career in national politics that dates back to 1973 — before some of his opponents were even born. Biden, who has waged two previous presidential bids and served eight years in the Obama White House, has arguably been vetted more thoroughly than any other candidate.

“If he has to respond to everything he did in 1974, it’s going to be an unpleasant campaign for him,” said Ross Baker, a Rutgers University political scientist who specializes in the Senate. “I think he has to make a statement right at the outset that times have changed. He has changed with the times, as have many people.”

Blasts from the past

But despite his time on the public stage, Biden’s record could get a new airing and his popularity could dip if opponents decide to seize on aspects of his past that have not aged well.

“He’s much too big of a fish to be ignored by his rivals, and they’ll have to tear him down,” columnist Matt Yglesias wrote for Vox in January. “The entire spectacle of once again re-fighting every intraparty battle from the past two generations would be bad for almost everyone at a time when Democrats should be talking about their ideas for the future.”

But Biden may be able to point to his more recent actions as evidence that his views have evolved.

He was one of 32 Democratic senators, for example, to vote in 1996 for the Defense of Marriage Act, which defined marriage as between one man and one woman. But by 2012, he had declared his full support for gay marriage on national television, propelling Obama, who had been lukewarm on the topic, to do the same a few days later.

Biden, a practicing Catholic, voted in the ’70s, ’80s and ’90s against federal funding for abortions and to override President Bill Clinton’s veto of a controversial ban on the late-term procedure termed “partial birth” abortions. Those views had evolved by the time he was in the White House. In 2012, he said the government does not have “a right to tell other people that women, they can’t control their body,” according to The New York Times. 

“Reproductive freedom is under threat in unprecedented ways and we hope that all potential and announced candidates vying for the Democratic nomination, including Joe Biden, will stand up for reproductive freedom in bold and decisive ways,” said Amanda Thayer, deputy national communications director of NARAL Pro-Choice America, an abortion rights group. 

Biden can point to his obligation as a senator to protect businesses in his state to explain his vote for the 2005 Bankruptcy Abuse Prevention and Consumer Protection Act, which passed the Senate 74-25. That measure made it more difficult to file for Chapter 7 bankruptcy protection and was considered disastrous for middle-class families struggling with credit card debt. But it was a boon to the banking giants headquartered in Delaware, a major employer of Biden’s constituents. 

Civil rights groups have largely considered Biden an ally, but he also has never run before in a field with several African American opponents, at a time when groups like Black Lives Matter are pressing candidates to confront issues of race head-on. As a result, he could face more pressure to answer for early positions on school desegregation and criminal justice overhaul.  

One of the first fights Biden waged as a young senator was his passionate opposition to court-ordered busing of students, which was unpopular among white voters in Delaware. The battle put him at odds with the country’s first popularly elected black Senator, Massachusetts Republican Edward W. Brooke, and much of his party.

Jason Sokul, a historian at the University of New Hampshire who has studied the episode, said he has not seen any evidence that Biden’s views about busing have changed.

“If he believes he was wrong, he could say he was wrong and he could attempt to come up with some legislation to try to make a dent in the problem of school segregation,” Sokul said. “But it’s not clear to me that he thinks he was wrong.”

Opening with apologies

In contrast, Biden has attempted to distance himself from some of the hard-line stances he took on criminal justice. The 1988 Anti-Drug Abuse Act he sponsored and the bipartisan 1994 Violent Crime Control Act he championed are now thought to have ushered in the era of mass incarceration.

“You know I’ve been in this fight for a long time. It goes not just to voting rights. It goes to the criminal justice system,” Biden said at a Martin Luther King Jr. breakfast in January. “I haven’t always been right. I know we haven’t always gotten things right, but I’ve always tried.”

Marc Mauer, executive director of The Sentencing Project, a research and advocacy group that promotes an overhaul of sentencing laws, said members of both parties at the time were competing to show who could be the toughest on crime.

“I don’t think that absolves knowledgeable leaders for being responsible for understanding what was going on,” he said. 

He also noted, however, that when Biden was vice president, he advocated a relaxation of strict sentencing laws, which ultimately was signed into law by President Donald Trump in 2018. “If he were to be in the White House, I would be cautiously optimistic that he would carry forward the reform agenda that he shared in the Obama administration,” Mauer said.