While it is still early days, the two frontrunners for the 2020 Democratic nomination are former Vice President Joe Biden and Senator Bernie Sanders of Vermont. (As of this writing, only Sanders has formally announced, although it seems likely Biden will soon join the race.) Polling has Biden and Sanders polling roughly the same among primary voters in New Hampshire. The two politicians respectively embody the two warring wings of Democrats. Biden, a U.S. Senator from 1973 to 2009, has been a leading party notable since the 1990s, leaving him with a record of much of the same decisions and policies for which Hillary Clinton was criticized from the left in 2015 and 2016. Sanders, with momentum still behind him from that insurgent 2016 run for the nomination, has the name recognition and the integrity to mobilize left-leaning Democrats to his bold, system-altering economic reforms. With every day bringing new public outrage about broken institutions and relative deprivation to past generations, it is entirely feasible that a Sanders nomination or even a Sanders presidency could be a reality. While Republicans are (in some cases begrudgingly) lining up to hold their noses and re-elect Donald Trump, smart money suggests Trump will do more harm than good to his chances once he’s back on the campaign trail. The more challenging hurdle for Sanders may be getting his party to unite behind him given the fractured state of the Democrats.

Let us imagine that Sanders does muster a grassroots political revolution over the arrayed forces of reaction and privilege. How successful would he actually be? Most Sanders supporters would dismiss the question as too hypothetical, too negative; just because something will be difficult does not mean it should not be tried. This is more than naïve idealism; this is the life-impulse that gets human beings out of bed in the morning. Nevertheless, people building a better world should not proceed blindly or ignorantly. It is worth examining how some previous recent presidents elected with a mandate of ambitious reform and reconstruction fared in carrying out their subversive agendas. Franklin Delano Roosevelt created a social welfare government, its economy still capitalist but its society supported by more government benefits and regulation. Ronald Reagan was the product of a conservative counterrevolution to the New Deal as well as civil rights, decades in the making. Barack Obama won with a groundswell of support in the wake of the 2008 financial crisis, but despite having campaigned as a reconstructive candidate, once in the White House maintained the non-ideological technocratic management style of his predecessors. Most recently, Donald Trump scored an authentic populist victory over the Beltway establishment, but those parts of his platform that most appealed to his angry right-wing base have floundered: building a wall along the U.S.-Mexico border, a full-on ban on Muslim immigration, prosecuting Hillary Clinton for real and imagined crimes and misdemeanors, and so on. The evidence would certainly suggest that, even in the best-case scenario where President Sanders has the support of most of his party as well as a majority in Congress, four years of gridlock would be more likely than eight (or even four) years of radical reforms.

Political scientist Stephen Skowronek documented this phenomenon in his 1993 book The Politics Presidents Make: Leadership From John Adams to George Bush. Unlike many other works that fixate on the individual personalities and choices of the presidents, Skowronek examined the “institutional logic of political disruption.” He observed that, as the office of the president evolved as an institution, the ability for its occupants to disrupt the old order and articulate a new consensus has shrunk. It is no coincidence, he argues, that the two most successful political revolutions in U.S. history—the Jeffersonian repudiation of federalism in 1800 and the rise of Jacksonian populism in 1829—occurred when the U.S. was young, before organized interests and institutions able to check the presidency matured. As Skowronek puts it: “The ‘rise’ of the presidency as an instrument of government has delimited its political range as an instrument of reconstruction.” It may seem absurd that the modern President of the United States, who has the power to assassinate virtually anyone by drone strike or invade most countries independent of Congressional approval, should be thought of as having constricted power. Yet even these actions must meet certain parameters. It is acceptable to authorize a drone strike on a suspected ISIS militant, but it would be unacceptable to summarily execute a banker responsible for wrecking the global economy. It is fine to bomb a low-income country with a regime hostile to Western business interests in the name of “humanitarian intervention,” but it would unthinkable to bomb the human rights-abusing, ironclad authoritarian regimes that defend our strategic interests abroad and/or provide us with important resources. The question is not so much “What can the President do?” so much as “Can the President actually do what he/she wants to do?” To paraphrase Marx, “Human beings make history, but they do not make it as they please.” To better understand what the walls and ceilings on when it comes to a future reconstructive president, we should look at some past examples.

Franklin Delano Roosevelt won the 1932 presidential election in a landslide, the stock market crash of 1929 and the Great Depression setting the stage for a wave of economic populism. While hardly from humble origins, Roosevelt embraced his role as a reformer. For him, the “new” in the New Deal would mean that a “new order of things designed to benefit the great mass of our farmers, workers, and businessmen would replace the old order of special privilege in a Nation that was completely and thoroughly disgusted with the existing dispensation.” In many ways, this evoked the anti-aristocratic appeals of Jeffersonian and Jacksonian democrats, but by the 20th century class tensions had taken on a distinctive character. Thanks to industrialization and the trade union movement, it was organized, agitating factory workers as well as farmers taking on bankers and industrialists to combat economic inequality and unfair labor practices. Midterm elections in 1934 and his own re-election in 1936 illustrated how much popular support FDR possessed. Popular support, however, was often not enough. In 1934 business leaders and conservative Democrats founded the American Liberty League to marshal opposition to the New Deal. FDR did not personally dominate the Democratic Party the way its founder Andrew Jackson had done. In 1934 the Supreme Court ruled that the National Recovery Administration, a New Deal agency, was unconstitutional, even though many of its provisions would be incorporated into the still-enforced Wagner Act, which guarantees the rights of private employees to form unionize, collectively bargain, and strike. It is doubtful the New Deal would have been successful as it was had it not been for the key support of the coalition of farmers organizations, labor unions, and small business owners that rallied behind FDR. When Japan attacked the U.S. in 1941, domestic opposition to Roosevelt diminished as the country was gripped by patriotism. Roosevelt would not live to see the transformation of the U.S. under his successors Truman and Eisenhower into what the latter called the “military-industrial complex,” with the Pentagon and arms manufacturers emerging as powerful new organized interests in their own right. In the end, the New Deal was only partially successful: it increased the capacity of the government to provide social services to its citizens and also brought important new regulation to the private sector, but power stayed narrowly concentrated politically and economically among a narrow group of elites. What’s more, World War II and the Cold War directed national attention away from improving domestic conditions to an aggressive foreign policy of “pursuing U.S. interests,” i.e. consolidating and enforcing its hegemonic influence across the globe.

This influence would be especially felt in South Asia as a series of presidents following in the moderate liberal mold presided over the growing U.S. military presence in Vietnam. The U.S. was a bellicose force around the world, intervening directly or indirectly on almost every continent; several generations of U.S. citizens lived in the shadow of nuclear Armageddon. Meanwhile, government action on equal rights for African-Americans, women, and other repressed communities continued slowly. By the 1960s enough opposition to imperialist foreign policy and insufficient progress on social justice culminated in growing unrest. The presidency of Richard Nixon was meant to constrain this strife, but ultimately it brought the office to its weakest point. It was Jimmy Carter, however, that Skowronek lists as the “disjunctive” president of this period, who attempted to garner enough authority via popular support to reform the moderate liberal consensus as a moderate liberal himself. Unsurprisingly, in an election where voters wanted change, they chose to elect Ronald Reagan as the figurehead of an right-wing movement consisting of big business, war haws, and evangelical Christians.

The most significant domestic accomplishment of the Reagan presidency was the slashing of federal spending through tax cuts for the wealthy, meant to “trickle down” to low-income groups. The top tax rate was dramatically lowered from 70 percent to 50 percent. At the same time, Reagan satisfied the military-industrial complex by raising defense spending and resuming a more aggressive, pro-intervention foreign policy. But when it came to repealing significant civil rights legislation like the Voting Rights Act or privatizing New Deal programs like Social Security, the Reagan presidency did not seriously pursue these lofty conservative goals. Racial equality had reached a level of cultural acceptance that a return to segregation was unthinkable; the “compromise” had to be to hem most African-Americans into violent dilapidated neighborhoods. As to “entitlements,” voters tended to enjoy programs that helped supplement their health insurance costs or allowed them to enjoy some financial security in retirement. To the conservative intelligentsia, such programs for the “general welfare” opened the door to dangerous possibilities of public ownership and universal health care. Moreover, it was hoped that sharp reductions in spending on “entitlements” would offset the large loss in revenue the government suffered as a result of the tax cuts, threatening to increase the deficit.

Unfortunately for Reagan and the conservative movement behind him, programs like Social Security and Medicare had become third rails for organized interests, such as the AARP. Even if most U.S. citizens were unsatisfied with the old moderate liberal consensus, they did not want to give up their retirement benefits or unemployment insurance, especially in the midst of the deep recession of the early 1980s. Reagan had more success in taking on and defeating the labor movement, which had largely atrophied and become more docile since the New Deal era. During the Cold War, unions like the AFL-CIO had taken pains to join in on anti-communist hysteria and distance itself from the labor agitation of the past. Consequently, they had no zealous base to call on when Reagan and his supporters worked to weaken and bust labor laws and other protections for workers against the avarice and abuse of their employers. Still, the clock was not wound back all the way; legislation like the Wagner Act remains on the books, although recent Supreme Court decisions suggest the war on labor protections goes on.

Reagan was also a marked departure from more successful reconstructive presidents like Andrew Jackson and Abraham Lincoln because he was not so much driven by a personal vision as he was an actor serving as the “face” of the new order. There was a popular perception that he was an senile cretin with a penchant for naps, and that it was powerful figures behind the scenes, well-known personalities of U.S. conservatism—Secretary of State Alexander Haig, Secretary of the Treasury James Baker, et al.—that were making real decisions in conjunction with allies in multinational corporations and right-wing think tanks. For example, escalations in military spending not only satisfied the bellicose worldview of conservative Cold War warriors but was also good business for those many industries with a stake in building fighter jets, aircraft carriers, etc. Reagan’s purpose was not so much as to galvanize the public to support his proposals, as FDR did when taking on his political enemies, but to serve as an eloquent cipher for the enormous bureaucratic, military, and financial institutions that had come to dominate the political landscape. As a former movie star, he was the exemplar of what has become a feature of modern U.S. elections: the shallowness of personality-focused public relations spin, with emphasis on individuals and their relatability instead of issues.

George H.W. Bush, Bill Clinton, and George W. Bush would all refine the model set by Reagan. None of these men mastered the “vision thing,” as George H.W. Bush called it, but the latter too at least were proficient at the celebrity-style of presidential politics. Politically, they would be defeated in their more ambitious proposals (health care reform for Clinton, privatizing Social Security for Bush) and largely settled into their role as managers. Clinton did not hesitate to take on “welfare reform” and “law and order” when Republicans won a landslide in the 1994 midterm elections, gutting what remained of the social safety net for poor people and deepening harassment and unjust incarceration of African-Americans. Widely considered incompetent when he first took office in 2000, George W. Bush saw domestic opposition dry up after the September 11, 2001 terrorist attacks, but his major accomplishments—the PATRIOT Act and its legacy of mass surveillance, the creation of the Department of Homeland Security, starting two wars with no exit strategies—could have only happened against the backdrop of the 9/11 attacks. By the time of the 2008 financial crisis Bush had largely squandered the goodwill and relative carte blanche he had been allowed in executive action. In the bailing out of the very institutions that had caused widespread unemployment and foreclosures, the collective U.S. government revealed itself as more beholden to organized interests (at least, those with the most resources) than to their constituents. In many ways, the conditions were eerily reminiscent of the U.S. political environment in 1932, with public outrage at political and financial elites at a fever pitch. Indeed, on November 2008, TIME magazine published an issue whose cover was Barack Obama edited into an image of FDR in a car, a cigarette holder poised between smiling teeth.

Obama would prove far more reminiscent of Reagan than FDR. He spent his political capital on a signature issue, this time health care rather than tax cuts. “Obamacare” would be a far cry from the sort of public health insurance that exists in most industrialized countries, with no “public option” but instead mandating the purchase of private health insurance plans. Unlike FDR, who used workers’ groups to challenge his opponents, Obama willingly sat down and compromised with the private interests that control the health care industry, from the insurers to the pharmaceutical companies. In a sense, this was a capitulation with no war, and while “Obamacare” represented an improvement over what came before, it showed how weak the presidency had become in taking on private interests. It was the interests themselves making policy rather than politicians imposing it on them. Obama’s 2008 campaign was innovative in its use of social media to win small-scale donations and increase voter turnout, but there was a deliberate choice to not use this sophisticated communications operation to turn his supporters into a legion of incendiaries and instigators pushing for a radical agenda. In his candidacy, some of the most fervent Obama supporters were in the far-left ranks of the party; by the end of his presidency, he had made it hip to be square again. In a word, his legacy would be best described not as “reformist” but rather “compromising.”

Obama would show this flair for compromise by his softening on a number of campaign promises, such as holding to account officials who had authorized the use of torture (“Look, we tortured some folks,” he would famously admit) as well as closing our prison outside U.S. legal protections in Guantanamo Bay. Rather than breaking with the old order as many expected, Obama sought to patch it up, to tinker around the margins rather than threaten the status quo. Despite his “steady hands” and aversion to controversy, Obama’s identity as an African-American would prove intolerable to a large segment of the conservative electorate, ironically inspiring the sort of right-wing revolt that logic said his mild manner would not engender. The idea that a non-white (and, according to some conspiracy theories, non-Christian and non-American) “radical” could hold the White House suggested to the far-right that the identity of the U.S. (or, at least, their racist interpretation of it) was in crisis. This, along with the changing demographics of the country and growing inequalities wrought by globalization, culminated in an explosion of unexpected furor and energy behind a much more aggressively reconstructive president than Obama, Donald Trump. Unlike Obama, who used his charisma to sell policies or win votes, Trump was a demagogue, not shy about encouraging his followers from fighting with their many enemies, sometimes literally.

As noted previously, the most headline-grabbing Trump proposals that he fed to his alt-right base have largely been stultified. His vows to “drain the swamp” in Washington, D.C. were disproved by his decision to populate his cabinet with the military officers and former investment featured so commonly in other Republican and Democratic administrations. The restrictions placed on the office of the president and presidential actions have (mostly) won out over Trump. When Trump supporters blame the “deep state,” a (fictional) shadow government, for frustrating their hero, they are rather lazily playing on the cliché canard of an all-powerful secret society common in popular culture, a variation on the Illuminati. The reality is that there are indeed forces at work seeking to preserve the status quo because it is stable and profitable, but they do not hide in the shadows. Identifying them is as simple as answering the classic question: Cui bono? Who benefits? It is the multinational corporations whose profits have soared while wages have stayed stagnant; it is the bankers whose bonuses grow fatter with every risky speculation that puts the integrity of the global economy at hazard; it is the generals and admirals whose budgets are regularly increased despite the absence of any rival superpower who could equal us in conventional warfare; and it is the high-tech industries that supply the generals and admirals (and increasingly police officers) with bigger and better toys. They are not as omnipotent as the imaginary “deep state,” as the disappointing conclusion of the Mueller report demonstrates. Nevertheless, there are perfectly legal means for them to influence politics, from determining media coverage to legalized bribery via lobbying. Corporations are people, after all, and money is speech.

Bernie Sanders is no Bolshevik. As he himself has said, “How radical do you have to be to do what every other major country in the world does?” His proposals are consistent with the reforms pursued by the moderate liberals who preceded Reagan: domestic programs funded through regressive taxation, with the wealthiest taxed the most, to aid the neediest and most vulnerable. Yet, if mainstream media coverage is anything to go by, universal health care or stimulus spending to address climate change are unrealistic, dangerous, unthinkable. If Sanders somehow manages to defeat a litany of challengers as well as Trump (and neither is certain), it can only be expected that the efforts to ridicule and vilify his agenda will intensify. For a sample of what to expect, consider the amount of scrutiny and criticism that has been directed to the leader of the British Labour Party, Jeremy Corbyn, a representative of that party’s left-wing. Corbyn has so far endured smear campaigns painting him as unpatriotic and anti-Semitic. The right-wing leaders of the party have tried to replace him (unsuccessfully, as they lack popular support) and recently a number of them quit to start their own centrist party. Even though the governing Conservative Party is at war with itself over Brexit, Labour is itself divided over accepting a reconstructive platform. It would be reasonable to assume the Democratic Party would react the same were Sanders its leader, be it as nominee or president. Yet, whereas British culture prides itself on restraint, U.S. culture is as subtle as a redneck firing a semiautomatic weapon atop an ATV. The hysteria that would accompany a Sanders presidency would likely make the present state of affairs seem sane and civil, as unfathomable as that might be. Such a prediction, however, would be consistent with Skowronek’s thesis and the empirical trend of U.S. presidential politics.

What is to be done? If the case of FDR and the New Deal is any example, an army of organized left-wing activists will be required to come together to resist elite attacks on reformist proposals. Sadly, the unions in the U.S. are a shade of what they used to be, although that is starting to change. Rather than maturing into social movements, left-wing responses to the present crisis—from Occupy Wall Street to the Women’s March—have adopted festival atmospheres, lighting up for a brief moment and then petering out before the serious work gets done. While social media has increased the ability of activists to organize and be heard, it also promotes the idea that posting online will itself be a catalyst for change. Collective action and civil disobedience are historically what have gotten the goods, not petitions and hashtags. Unfortunately, most U.S. citizens still begrudgingly “trust the process,” that the system will reverse its decline on its own. It is likely that they underestimate the powers of institutional inertia they are up against.