America, a growing number of legal, political science, and other scholars argue, is vulnerable to democratic backsliding — and it isn’t clear if a Democratic win in tomorrow’s midterms will change that trajectory.

Democratic backsliding refers to the subtle, gradual deterioration of democratic institutions and practices, the erosion of elements like free and fair elections, freedom of speech and association, and the rule of law. It isn’t the same thing as reversion: Few people think a sudden, dramatic collapse into dictatorship, like the fall of the Weimar Republic in Germany or the Peruvian “self-coup” of 1992, is likely in the near future. But a slower descent is entirely possible.

And the Trump administration and its Republican allies, specifically, have contributed to backsliding, especially through undermining competitive elections and the rule of law.

“The checks imposed in the government are much weaker than they were two years ago,” Aziz Huq, a University of Chicago law professor, told me, citing the failure of inspector generals to hold cabinet officials to account, Trump’s partisan attacks on prosecutors, and the disinclination of congressional Republicans to meaningfully challenge the president. “The checks imposed by the media are weaker because there’s been a concerted rhetorical campaign against the media that is associated with violence.”

It’s natural, then, to wonder if the 2018 midterms could represent a meaningful check on those trends. An opposition party-controlled chamber of Congress would curb Trump’s worse impulses through investigations, and a Democrat-controlled Senate could limit his influence over the judiciary.

But perhaps the most important impact on American democracy will be the lessons the election imparts on Trump’s fellow Republicans. Democrats taking back the House — the likeliest scenario according to polls — could leave Republicans with a sense that he’s vulnerable, and that they can afford to challenge him and join in investigations, reducing Trump-associated backsliding. Conversely, a Republican win could reinforce the idea that white identity politics works and that a party can pursue voter suppression and other anti-democratic moves and be rewarded for it.

The threats to American democracy can’t be resolved in one election. They involve big structural problems like the polarization of elites and politicians, growing hatred of the opposition party and deep emotional affiliation with one’s own party, and white anxiety over the loss of control over American politics and culture. But there’s reason to think those structural problems would be worsened by a Republican win.

If you care about democratic institutions, Republicans keeping Congress should keep you up at night

The likeliest outcome on Tuesday appears to be Democrats taking back the House, while Republicans maintain their hold on the Senate. As of Friday morning, FiveThirtyEight’s “classic” model assigns this a 69.8 percent probability: hardly a certainty, but a very good shot.

But the model also gives Republicans a 15 percent chance of keeping both chambers — certainly not great odds, but a real shot nonetheless. That’s the scenario that’s concerning.

A Republican hold will have normal policy outcomes; it will make another tax cut bill more likely, and could embolden the party to take another run at repealing Obamacare.

But in terms of democratic backsliding, regular policy outcomes like health care bills matter less than the willingness of Congress to challenge the president and his excesses. And that’s what should worry us. A good midterm for the Republicans likely means several things: a continued lack of congressional oversight, support for Trump’s efforts to remake the courts and attack the press, and little more than mild tsk-tsking of the over-the-top demagoguery that has characterized the first two years of Trump’s presidency.

What’s even more troubling is if a Republican victory suggested public opinion is supportive of democratic backsliding itself. A Republican win alone is not enough to show that. But Gisela Sin, a political science professor at the University of Illinois Urbana-Champaign who studies political institutions in both the US and Latin America, warns that authoritarian reversions in Latin America have typically happened with the support of a majority of the population, disgusted by Congress’s corruption and willing to embrace a more autocratic presidency.

The danger, for democratic institutions, is that a good night for Trump and Republicans will convince that party’s non-Trump leaders that how Trump has governed these past two years, and how he’s campaigned these last few weeks, is exactly what the American public wants.

Can Democratic gains halt backsliding?

A Democratic takeover of the House — the likeliest scenario at this point — can certainly help put a halt to, if not reverse, backsliding. A Democratic takeover of both the House and the Senate — a 15 percent likelihood, according to FiveThirtyEight — would be even more meaningful, posing a serious challenge to what has thus far been untrammeled rule by Trump.

One possible effect of a Democratic win in the House would be to push remaining Republicans in Congress, particularly in the Senate, to become more critical of Trump and support checks on his more anti-democratic tendencies: resisting phony “voter fraud” crackdowns, for instance, pushing back on his attacks on the press, and backing legislation to protect Robert Mueller and the independence of prosecutors more generally.

“If the Democrats take even the House, but certainly both chambers, the Republicans’ spinelessness may decline and that’s super important,” Robert Mickey, a political scientist at the University of Michigan who’s studied authoritarianism and democratization in the American South, said. “I don’t know if Lindsey Graham is going to be less current Lindsey, but if the Democrats take both chambers, Trump’s ability to shape or destroy Republicans’ careers will be shown to have been much weaker than they all feared.”

Beyond those effects, a Democratic takeover of the Senate and House will fortify and embolden Congress to serve as a check against the presidency. For one, the Senate is another branch that can engage in investigations that apply pressure to the White House.

In a recent paper, political scientists Douglas Kriner and Eric Schickler argue that the Senate Russia investigation — arguably the only serious congressional investigation involving Trump that has been conducted under Republican control of Congress — has exacted “considerable, and still growing” costs.

That, in conjunction with the Mueller probe, has “directly led to the enactment of sanctions legislation that contradicted Trump’s foreign policy goals,” they write. “More broadly, the Russia probe, and the media’s unfailing fascination with it, has been a significant drag on President Trump’s approval ratings.” A Democratic Senate would be able to engage in still more investigations of this seriousness and magnitude, over and above what the House alone could do.

But more importantly, the Senate has a power the House lacks: control over the judiciary, or at least control over which Trump nominees can make it through. If Democrats took over the body, Mickey said, “Trump might get some judicial openings, but his judicial pipeline is going to get a lot less successful.”

“We’ve seen a colonization in part of the courts by an ideology that is friendly to the Trumpian backsliding project, or the project in which democracy is considerably thinner than it is today,” Huq said.

“The court now tends to align with elites rather than with the less powerful,” he said. “The court, as empirical scholars like Lee Epstein have shown is more pro-business than it’s been in decades. … White plaintiffs win equality cases far more than non-white plaintiffs do. Christian minorities win more cases than any other religious minority or minority defined by sexual identity.”

That trend both runs the risk of undermining the rule of law by eroding the sense that groups get equal treatment in the courts, and undermines democratic self-government by making the courts less likely to ensure equal access to voting, to political power, and so on.

If Democrats were to take the Senate, they could arguably slow this change in the courts. But if, as is likely, they merely take back the House, then Republicans would be able to replace Ruth Bader Ginsburg, Stephen Breyer, and plenty of lower-court judges and accelerate the shift.

All that said, there are a few potentially troubling outcomes even if Democrats take one or more houses of Congress. Mickey noted that such a development runs the risk of encouraging more unilateral action from Trump, a kind of “constitutional hardball” that contributes to a concentration of power in the presidency, itself a democratic risk factor. So even if the Democrats have a good night, we may still not be out of the woods.

Democrats, in turn, might pursue a “tit for tat” strategy as the new majority party in one or both houses, undermining regular order and denying the minority the ability to offer amendments or participate in investigations. Harvard political scientists Steve Levitsky and Daniel Ziblatt have argued that “forbearance” by parties, in which they decline to engage in that kind of hardball even when provoked, helps preserve democratic institutions by foreclosing the use of technically legitimate techniques to undermine the rule of law, fair elections, and the like.

“Analysts of backsliding disagree on the importance of forbearance,” Mickey explained. “My sense is that some of this difference comes down to different assessments of the current dangers — those who think the current dangers are higher are more apt to say ‘screw minority rights, Democrats in power must crush their opponents before they get up off the mat.’”

Mickey also highlighted the fact that if Democrats retake the House, they’ll do so largely by defeating relatively moderate Republicans, which in turn pushes the Republican caucus as a whole to the right. “Still, though,” he said, “I think that Republican challengers in 2020 in suburban districts may have ‘learned’ (and I’m agnostic as to whether they’d be right) that white identity politics isn’t a dominant strategy for them.”

Lessons from abroad

There is some international precedent for electoral defeats helping end a process of democratic backsliding.

South Africa, in recent years, provides one possible model. Jacob Zuma, the third president since the country became a democracy in 1994, exploited his office for personal financial gain, and faced accusations of using state prosecutors to wage factional battles within his party, the African National Congress.

But in early 2018, he was forced out of office. “In South Africa, the ANC in 2016 lost a slate of very important municipal elections which they hadn’t been expecting to lose, because of judicial revelations of [President] Jacob Zuma’s corruption,” Huq said. “The loss in those elections persuaded leaders to abandon Zuma, who had been a catalyst and a driver of backsliding in the South African context.”

This was a gradual process (Zuma left office a year and a half after the elections) but was accelerated by the perception of a real electoral threat from the opposition Democratic Alliance.

There was also, until this past week, the case of Sri Lanka. President Mahinda Rajapaksa, who served from 2005 to 2015, oversaw the end the Sri Lankan civil war (while committing serious war crimes against the Tamil minority) and ran a regime Huq and his UChicago colleague Tom Ginsburg describe as “marked by nepotism, corruption, and a degradation of rule-of-law institutions such as courts, prosecutors, and the police”; it also featured crackdowns on journalists. The backsliding was halted in 2015 when he lost reelection for a third term.

That said, on October 26, risks of backsliding appeared to return as Rajapaksa’s successor sacked his prime minister (arguably unconstitutionally) and replaced him with … Rajapaksa, who is now serving under the president who beat him in 2015. (My colleague Jen Kirby explains more here.)

If Republicans have a good night on Tuesday, the idea that white nationalist and anti-democratic demagoguery pays will likely persist for Republicans — and may guide their politics and rhetoric these next couple years.

Sin, the University of Illinois-Champaign political science professor, noted that popular enthusiasm for dictatorial measures, and distrust of democracy, helped fuel Peruvian President Alberto Fujimori’s decision to dissolve Congress in 1993, and Hugo Chavez’s consolidation of power in Venezuela. “Authoritarianism has to come from society, not just the government,” she said.

Indeed, the day after Fujimori “suspended the constitution, dissolved the congress, sent tanks into the streets and rounded up political opponents,” according to the Washington Post, his approval rating leaped to 79 percent.

We’re a long way from that outcome. But a necessary precondition for Fujimori’s actions was a sense that the public would back him up. A Republican win could instill a similar sense in Trump. And it might already be instilling such a sense in some state-level Republicans.

Brian Kemp, the chief elections officer in Georgia and the Republican nominee for governor, announced an investigation into the state Democratic Party mere days before the election, in what certainly looks like an effort to swing the vote. North Carolina is, on Tuesday, considering amendments to move control over the judiciary and state ethics board from the executive to the legislature: a pretty blatant effort by the Republican-controlled legislature to disempower the Democratic governor.

A surprise Republican victory could send a dangerous message that they can make such anti-democratic maneuvers — and get away with it.

Sign up for the Future Perfect newsletter. Twice a week, you’ll get a roundup of ideas and solutions for tackling our biggest challenges: improving public health, decreasing human and animal suffering, easing catastrophic risks, and — to put it simply — getting better at doing good.