Editor’s note: See here for an update to this story.

There are some valid reasons for liberals to be less than thrilled with Hillary Clinton’s solid, unexciting, risk-averse choice of Tim Kaine as vice president. But one of the issues often cited by Kaine’s critics—abortion rights—is not one of them. Indeed, Kaine’s story is an illustration of how much the reproductive rights movement has moved the needle within the Democratic Party. And it’s also an illustration of one of the key points of Barack Obama’s speech at the Democratic National Convention on Wednesday: “We all need to be as vocal and as organized and as persistent as Bernie Sanders’s supporters have been.”

Some very astute writers have expressed concern about Kaine’s history on reproductive rights. “The very last thing we need is another person in the White House who further stigmatizes abortion,” writes Jodi Jacobson of Rewire. Clinton’s selection of Kaine, suggests Nora Caplan-Bricker of Slate, “begs the question of whether, on an issue that had seemed so near and dear to Clinton’s heart, we can be sure that we know where—or at least how firmly—she stands.” Responding to NARAL President Ilyse Hogue’s statement that “she chose Tim Kaine because she trusts the guy, and I trust her,” CUNY political theorist Corey Robin argues, “When Republicans say this kind of thing, we call it faith-based politics. Democratic skepticism, it ain’t.”

Kaine did indeed sign some bad anti-abortion legislation and take some bad anti-abortion stands when he was governor of Virginia. He’s a Roman Catholic who has said that he’s personally pro-life. But as Caplan-Bricker and Robin acknowledge, he has also had a flawless pro-choice record since becoming a U.S. senator, earning A grades from both NARAL and Planned Parenthood. Should we be concerned that Kaine will backslide—that the state-level politician is the real Kaine? 

This is not actually a difficult question: Kaine’s record as a senator is far more relevant. “[I]t’s hard to know,” says Caplan-Bricker, “whether Kaine’s new look reflects his own changing attitudes, or the changing shape of the Democratic Party.” But since he is the party’s nominee for vice president, the distinction doesn’t actually matter. He is going to represent the party’s strong consensus on the issue, which is reflected in the most strongly pro–reproductive justice plank in the history of national Democratic platforms. To what limited extent the vice president can influence abortion policy, he will follow this party line. What he “really thinks” about abortion isn’t relevant to how he’ll act in office.

To underscore this, before speaking at the DNC on Wednesday, Kaine came out in opposition to the Hyde Amendment, which prevents public funding from being used to obtain abortions (and hence represents a substantial barrier to poor women attempting to attain them). He’s not just defending Roe v. Wade, in other words, but coming out in favor of broadening abortion access. Representing a national Democratic constituency, Kaine is going to act differently than he did representing a state constituency in Virginia. He’s not going to change back unless the national party itself changes dramatically.

It’s worth pausing to reflect on how remarkable and welcome this change is. During the Clinton and Bush years, pro-choice national Democrats were often on the defensive, defending abortion rights in cautious rhetorical terms. There was a national epidemic of pundits calling on the Democratic Party to deemphasize abortion rights, and perhaps even give up on upholding Roe v. Wade altogether. The fact that supporting the restoration of federal public funding for elective abortions is now the minimum acceptable position for someone on the Democratic presidential ticket is a big deal—and the fact that Kaine had a prior history of compromise on the issue just makes the transition all the more striking. It’s hard to imagine NARAL’s Hogue’s quietly radical speech from Wednesday—in which she openly talked about having an elective abortion—being given at a national convention 20 years ago. 

Unlike Kaine, Hillary Clinton hasn’t changed her positions, but she has changed her rhetorical emphasis in ways that show the power of the movement for reproductive rights within the party.

This is how politics works. In general, ambitious national politicians follow their coalitions rather than impose their will on them. One classic example would be same-sex marriage—a determined movement compelled President Obama to abandon his nominal opposition. More importantly, the movement created a context in which all four of Bill Clinton and Obama’s Supreme Court nominees would vote to create a national right to same-sex marriage. Within the Democratic Party this question is now settled, and Hillary Clinton’s opposition to same-sex marriage (like Kaine’s erstwhile squishiness on same-sex marriage) is about as relevant as Lyndon Johnson’s previous vote against anti-lynching legislation was in 1965.

Another example of the phenomenon is both Barack Obama and the Democratic platform calling for an expansion of Social Security benefits, after decades of elite Democrats talking about the need for “entitlement reform” (despite the utter lack of any voting constituency for such policies). Barack Obama didn’t change the party— the party changed his positions.

This doesn’t mean, of course, that the Democratic Party’s constituencies should be complacent—quite the opposite. Not only do the gains on reproductive freedom need to be preserved, there are numerous other issues—from criminal justice to student debt to the minimum wage to gun control—where the direction of the party has been encouraging, but the fight is far from over. And there are other issues— most notably trade and financial regulation—where there is still real division within the party and where the choice of Kaine is not encouraging. But if his position on abortion is any indication, Kaine is, like most reasonable politicians, willing to evolve as his party does.