You might think that securing the White House, Senate, House of Representatives and a majority of seats on the Supreme Court would enable a party to practically dictate laws and policy. But so far, unified government hasn’t worked out too well for Republicans. The GOP has controlled both houses of Congress and the presidency since January but has no major legislative accomplishments to show for it. President Trump finally managed to close a big deal last week, to stave off a government shutdown and Treasury default for the next three months and secure hurricane disaster relief. And yet he cut the deal with Democrats — against the wishes of GOP leaders.

One thing the Republicans have done, however, is demonstrate that controlling government isn’t enough to govern. Since the U.S. system is designed to slow down and complicate attempts at change, even parties in control of the whole government have to learn how to navigate it. What makes that so hard? There are several things that a majority party needs in order to convert political victories into legislative ones, and the GOP doesn’t have them.

A prioritized agenda

This one seems obvious but can be deceptively difficult. Research shows that agenda control is a key source of power for the majority party in Congress. For a party to effectively implement an agenda, it has to (i) agree on what that agenda is, and (ii) how that agenda should be prioritized. The first part isn’t a given; Republicans largely support lower taxes, for instance, but — as the recent healthcare debate showed — they are less unified on health care policy.

Even when there’s agreement on the issues, parties must also decide on which ones to focus. Democrats, for example, controlled the White House, Senate and House in the post-New Deal era, through most of Harry Truman’s presidency, from 1961 through 1969 under John F. Kennedy and Lyndon Johnson, and again from 1977 to 1981 when Jimmy Carter was in office. During this time, they had to decide what policy goals to prioritize: economic reforms, health care coverage, arts and education, rural development, urban revitalization, civil rights? Some leaders, like Johnson, were able to tie many domestic issues together, while others, like Carter, came off as unfocused. Health care reform wasn’t prioritized and it remained on the Democratic to-do list all the way to the presidencies of Bill Clinton and Barack Obama.

Modern Republicans face an additional problem. Much of the party’s stated governing ideology rests on the premise that “government is the problem,” which makes it difficult to develop a coherent agenda for determining what the government should be doing. And currently, there isn’t much else unifying a party fragmented along lines of ideology, openness to compromise and support for the president.

Trump’s own approach to policy, meanwhile, hasn’t helped the party set priorities. He hasn’t clearly articulated what he wants the GOP to focus on, jumping from infrastructure to taxes to health care to immigration, and from controversy to controversy. He has also promised a number of governing outcomes – better health care coverage, stronger national security, a better economy – but he’s often short on the details about what kinds of policies might achieve them. Legislation tends to die in the course of working out the specifics, and without a stable, widely shared set of priorities, it can be hard to achieve anything.

Public support

Whatever agenda emerges, it helps a lot if it has public support. Public opinion doesn’t always direct policy, of course. But members of Congress tend to be motivated by an interest in reelection, and don’t want to be caught on the wrong side of a national debate.

The GOP is finding this out the hard way. Some of the few core positions that have been staked out by Republicans in Congress — such as bills to repeal the Affordable Care Act — have proven very unpopular. Trump also ran into this problem with the Russia sanctions bill: He opposed it, but widespread public support translated into veto-proof majorities in Congress.

In contrast, the mid-century Democratic Party had lots of disagreements, but its major agenda items, such as Medicare, were generally popular with the public. Historian Julian Zelizer has explained how Johnson’s extensive agenda — arts funding, fair housing, immigration laws — was successful, in part, because the electorate had voted in a liberal Democratic Congress in 1964, signaling support for a liberal policy direction.

Similarly, the GOP has successfully enacted tax cuts, which are usually popular, on several occasions. But public support for the party’s social agenda has declined; many more people support same-sex marriage nowadays, for instance, and there’s been a recent increase in support for marijuana legalization.

The GOP faces another challenge here: Trump won the Electoral College but not the popular vote. This matters for perceptions about whether he has an electoral mandate for his policies, which can sometimes influence how Congress acts. Some research suggests that members of Congress are more likely to support the White House’s agenda, at least in the short term, when they perceive an election to have been a mandate. As a result, the preferences of Trump’s core supporters are not always in line with the majority of the country.

A way to address internal divisions

Even with a governing agenda and public support, there will be disagreements over specifics, clashes between factions and disputes over resource allocation. Institutions can help resolve these disputes — especially organizational rules in Congress that create incentives for compromise. The strong committee model of the mid-20th Century provided this: Congressional committees enjoyed sole jurisdiction over their issues, and often worked across party lines. Under this system, elected official could be responsive to the needs of their districts, and worried less about party discipline.

This approach wasn’t perfect, of course. There were plenty of conflicts, and critics complained about the lack of party discipline and ideological definition. But it did allow for greater legislative productivity than we see today. Strong committees were replaced after the reforms in the 1970s (and another set of changes in the 1990s) that empowered party leadership, creating a structure that rewarded party loyalty and often discouraged ideological diversity.

Ideological diversity brought its own negatives, of course, including tolerating objectionable viewpoints for the sake of forming a wider coalition. We can’t talk about the mid-century Democratic Party without considering its Southern contingent, which held back progress on civil rights and also pushed back against issues like labor and wage protections that might benefit black workers. Mid-century Democrats compromised with their racist faction, sometimes sacrificing the interests of racial minorities for the sake of moving forward on policy.

The Republican Party now includes the successors to this Southern faction, as well as immigration hard-liners. But the political climate has changed since the 1960s. Many overtly racist attitudes have fallen out of favor. While New Deal Democrats sometimes governed by accommodating racists (a practice with a lasting, damaging legacy), those kinds of compromises may no longer be politically viable.

The U.S. system isn’t set up to let majority parties just do what they want, as I mentioned above. Protections for the political minority are built into the system: The Electoral College and the Senate protect smaller states from being dominated by more populous ones, and part of the role of the judicial branch is to protect minority rights, when necessary, from the will of the majority.

So governing as the majority party requires know-how. Since 1981, however, neither party has held both chambers of Congress and the presidency for more than four years (and then only once). So neither one has had much time to learn the tricks that help majority parties govern.

Instead, both often act like minority parties, engaging in what political scientist Frances Lee calls a “perpetual campaign”: Since most of the time either party stands a realistic chance of winning a majority in the next election, both parties have an incentive to compete rather than cooperate. Refusing to cooperate proved especially advantageous politically for Republicans during the Obama years, when they could rally around opposition to the president’s actions and object to government overreach.

Now, with Trump in office, Democrats are the ones with little incentive to cooperate. And there are still some Republicans behaving as though they’re in the minority. Those dynamics give the GOP very little room for error. The party has only a thin margin in the Senate, with 52 seats, so they can’t afford a lot of defections even on votes where a simple majority is enough. Trump opponents, meanwhile, have also had some success in the courts, which have been especially sympathetic to objections against the administration’s travel bans.

So what’s the outlook for the GOP as a governing majority? Various public breaks between Trump and congressional Republicans — including the most recent one over the debt ceiling — illustrate that the GOP coalition hasn’t yet figured out how to overcome its differences. But that’s a hard lesson to learn, let alone apply for any length of time. The coalition of New Deal-era Democrats eventually fell apart, after all — once they finally addressed the challenge of civil rights, the party’s hold on majority status started to crumble under the weight of disagreements over this and other policies.

An opposition party has the luxury of a unifying objective — pointing out the shortcomings of the majority. As the musical Hamilton tells us, “governing is harder.”