When Joe Biden became the first national leader to publicly support same-sex marriage in May 2012, less than half the country agreed with him, according to a Gallup poll that December. Only six states and the District had legalized same-sex marriage; a few dozen others had statutory or constitutional bans in place. But Biden — the same man who in 1996 voted for the Defense of Marriage Act that defined marriage as “between one man and one woman” — said he was “absolutely comfortable” with gay and lesbian couples being “entitled to the same exact rights, all the civil liberties” as heterosexual married couples. Biden’s career is defined by this trajectory: starting from a more moderate or conservative position on an issue and evolving over time with the party toward a progressive stance, often leading on it.

Progressives, particularly former supporters of Sen. Bernie Sanders, worry that Biden cannot be trusted to advance their values. They say he’s a centrist — or even a conservative — Democrat, pointing to past votes and rhetoric at odds with the progressive worldview. Some progressives say they won’t vote for him against President Trump, and others allow that they’ll do so grudgingly but then support a primary challenge against him in 2024 if he wins. One former Green Party organizer put it this way: “How could I in good faith tell someone to vote for someone who I don’t agree with on any issue? I can’t. No. Absolutely not.”

It’s not wrong that Biden has in the past embraced positions the left today sees as unacceptable. But it’s also true that, in almost every instance, he has moved along with the shifting consensus in his own party — and finally led on that consensus. Those who worry Biden won’t absorb enough of Sanders’s values and positions — whether on climate change, holding corporate corruption accountable or ensuring relief on crushing student debt — should consider his history of evolution. As the Democratic Party has updated its views, Biden has demonstrated consistently that he does, as well.

Despite Biden’s conservative-friendly reputation, he ranked among the top quarter of senators in liberal ideology while in the Senate — firmly at the median point of the Democratic Caucus — according to analysis from UCLA’s respected Voteview project. While this meant that at times Biden went with conventional wisdom and didn’t move ahead of the party on important issues such as the 1994 Crime Bill or that vote on DOMA, his resonance with moderate and conservative voters has helped to move those Americans on several progressive issues. He leverages his record as an incrementalist to bring voters leftward with him.

When Biden came into the Senate in 1973, he believed Roe v. Wade was “wrongly decided.” In 1974, he told Washingtonian magazine that Roe “went too far” and doubted that a woman has the sole say over her own body. Throughout the ’80s, he exasperated both abortion and antiabortion advocates. Although he won praise for pummeling failed Supreme Court nominee Robert Bork over birth control bans as Senate Judiciary chairman and supported giving members of the military access to abortion services, he also repeatedly voted for the Hyde Amendment, which bans federal dollars for abortion services in most cases. But by the time he launched his 2020 campaign, Biden had a 30-year-long record of supporting Roe. He also renounced the Hyde Amendment last year, despite the fact that it still has support among a majority of voters.

Biden’s evolution on same-sex marriage mirrors his change and leadership on other issues in the LGBTQ movement. He went from voting for the heinous and confusing “Don’t Ask, Don’t Tell” (DADT) policy in 1993 to supporting the failed Employment Non-Discrimination Act (ENDA) in 1996, which would have banned discrimination on the basis of sexual orientation. He later successfully fought for the repeal of DADT and now supports the Equality Act, legislation that would ban all forms of discrimination against LGBTQ people at the federal level. He presided over same-sex marriages during his tenure as vice president and, just before the 2012 election, called transgender rights “the civil rights issue of our time” when it wasn’t quite on the radar of many politicians. When Danica Roem of Virginia became the first openly transgender person elected to any state legislature, a poignant photo taken after Biden’s congratulatory call to her went viral. In 2018, he wrote the foreword for a memoir by Sarah McBride, a friend of his late son Beau Biden and the first openly transgender person to speak at a major party’s political convention. She’s now running for the Delaware state Senate and praises Biden for his leadership.

Sen. Kamala D. Harris notably criticized him early in the primary for not only his friendliness toward segregationists — such as bragging about his ability to form working relationships with senators who held self-proclaimed white supremacist views — but also his opposition to busing in the ’70s, a period during which he argued that school districts should find other ways to integrate instead of federally mandated busing. He also supported the 1994 Crime Bill (as did Sanders), which placed a profoundly racist burden on people of color in this country in myriad ways and helped bring about the mass-incarceration crisis that both parties are now trying to unwind.

But Biden, who once said he wanted a crime policy where “we do everything but hang people for jaywalking,” offers a platform with substantial criminal justice reform, including the elimination of the death penalty, ending the federal government’s use of private prisons and decriminalizing the use of cannabis (while expunging all prior cannabis convictions). Similarly, while in the 1980s he pushed legislation that created a disparity in sentencing between crack and powder cocaine, in 2007, he proposed eliminating the gap, which created harsher sentences for black citizens. He says he wants to enact it retroactively if elected. Biden became the presumptive nominee largely because of the strong support of black voters. He received more endorsements from members of the Congressional Black Caucus than every other presidential candidate combined. Harris heartily endorsed him as “a leader who cares about the people and can unify the people,” and she is considered a favorite to be Biden’s running mate.

He also has a record of building trust among progressives who might be wary of him. When they were both in the Senate, Biden was reportedly among the few who treated Sanders with respect, which notably played a role in Sanders’s rejection of calls by his staff to attack Biden during the primary. Similarly, before she was a senator, Elizabeth Warren clashed with Biden on a bill that made it harder to file for bankruptcy. But Biden has since endorsed Warren’s legislation plan, which includes repealing parts of that law. In her endorsement, Warren called Biden “a partner who’s committed to getting something good done for this country.”

His recent leftward shift on other economic policies is notable. When he was vice president, Biden supported raising the minimum wage to $10.10 an hour but in his first campaign speech, he called for raising it to $15. As he was leaving the vice presidency, Biden has also said he regretted his Senate vote to repeal Glass-Steagall, which separated investment and retail banking. On education, Biden went from supporting only free community college to last month announcing he would support public colleges and universities tuition-free for families making up to $125,000.

Progressives don’t need perfection. We need someone willing to listen to criticism, and Biden has consistently proved himself to be that person. Progressives can take heart knowing that he is a candidate who is eager to move toward us. In contrast to a president who doesn’t take responsibility for his own mistakes, one who substantially evolves is a welcome change. One might even call it progress.