The crowded Democratic field offers a lot of questions about policy, “electability,” experience, and ideology. But one thing is pretty clear: The candidates are comfortable presenting themselves as clear alternatives to Trump and promising that their leadership would make a clean break from the style and policies of his administration.

Party polarization makes this unsurprising, but it’s also a sign of what’s referred to Stephen Skowronek’s theory of political time as “reconstructive politics.” Presidents who come in with freedom to completely reject the ideas, commitments, and influential figures of the past have a lot of opportunities to reshape their own parties, to remake political institutions, and to set the tone for politics for decades to come.

The scholarship on reconstructive politics in the Reagan era has focused a great deal on how difficult it is to remake governing institutions — it’s difficult to get rid of parts of the federal government, as those institutions tend to be popular with the constituencies they serve and the people who work there.

As time has gone on, it’s become much harder to fundamentally change institutions of governance. But Reagan certainly shaped the rhetoric of politics and the priorities of his own party. Talk of Trump’s disjunctive potential has sometimes been accompanied by ideas about an impending period of repudiation and renewal, presumably under a new Democratic administration.

Now that there’s a group of candidates vying to head that administration, we can start to see how a reconstructive period might unfold, especially in the area of party politics.

Reconstructive politics often involves new issue priorities, and that looks to be an especially prominent theme for the Democrats heading into 2020. Immigration and the environment, which have rarely been leading issues for either party, are poised to influence the conversation and define Democratic positions. It’s also clear that at least some of the Democratic candidates have economic ideas for addressing inequality, the corporate environment, and social supports like child care.

Reconstructive leaders — think Franklin Roosevelt or Abraham Lincoln — often come from the center of their parties, not the most extreme or transformative faction. But they are informed by those actors and ideas. Because of the priorities and constituencies of the Democratic Party, it’s possible that a broad and deep policy reconstruction will be part of the next administration — at least in rhetoric.

Demands for transformation within the Democratic Party may not be limited to policy, though. The way we practice party politics has been in flux … well, forever, but the 2016 election highlighted dissatisfaction with political parties and their role in presidential nominations. The fissure between elites and party primary voters that 2016 hinted at already seems like it might be more prominent in 2020.

It’s very early, but Kamala Harris and Cory Booker seem to be dominating the “endorsement primary” while Joe Biden, Bernie Sanders, and Beto O’Rourke are the top candidates in recent polls. (Harris was fourth in the poll linked.) It’s possible that elite preferences will catch up to public opinion, or that polls will shift dramatically as some of the other candidates gain name recognition — Biden hasn’t even said whether he’s running yet!

But the strength of some of the candidates — O’Rourke and Sanders in particular, as well as the “moment” that Pete Buttigieg seems to be enjoying — showcases a particular kind of politics that emphasizes the ability to communicate on social media and rally a crowd.

The last two reconstructive presidencies — FDR and Reagan — chipped away at the foundations of party politics without dislodging core structures. Reagan was a successful party-builder, as Dan Galvin has pointed out, and Lara Brown has written about how FDR’s nomination showed how much he was a creature of his party. But FDR sought to work outside usual party channels and tried to redefine the Democratic Party as a New Deal party, with some success.

Reagan capitalized on insurgent rhetoric and on new nominating procedures that gave advantages to charismatic individual candidates. The coming Democratic reconstruction may take these anti-party ideas even further, reminding us that as reconstructive presidents alter the agenda and build up institutions, they also sometimes destroy them.

Accomplishing an ambitious policy agenda without a robust party might be harder than people think, and a successful reconstructive leader will think about how to build institutions that perform the functions of parties in ways that their constituents will find legitimate.

The current Democratic field stands out both for its historic diversity and for its number of candidates without traditional qualifications. Buttigieg is the mayor of a fairly small city. O’Rourke just lost a statewide campaign. Sanders has been in Congress for a long time, but has long identified formally as an independent, not a Democrat. These kinds of appeals and credentials seem to be important to at least some segment of the Democratic electorate.

This style of politics seems to go along with the ability to appear, if not ideologically pure, then removed from a problematic or compromised record. Yet the Democratic electorate is also heavily populated by women and people of color, and candidates from these demographics may have a harder time skipping over the traditional pathways like serving as senator or governor, or building fundraising and party ties. (Though it’s worth noting here that Buttigieg would be the first openly gay nominee or president, and Sanders would be the first Jewish presidential nominee or president. There’s a lot going on demographically in this cycle.)

This dynamic — more than serious policy differences among party factions — seems like a structural problem that is likely to provide the foundation for a conflict in the party that’s both difficult to resolve and possibly risky to talk about.

A struggling disjunctive presidency might make reconstruction look easy. The transition between two eras of party dominance opens up opportunities to change institutions, policy, and the terms of the political debate. But these opportunities only go so far, and constructive change takes real work. And maybe this is an instance in which studying history and social science can be useful as well as informative.

Reconstructive moments often contain the core elements of the eventual disjunction. If members of a new coalition can see some of these pitfalls coming, maybe a new set of leaders can choose to make politics with these challenges in mind.