This week, Americans go to the polls to decide the composition of the next Congress. President Trump’s upset victory over Hillary Clinton two years ago generated a surge of political engagement on both sides. Because this political fervor continues, the 2018 election has been perhaps the most highly anticipated midterm of our lifetimes.

Both campaign expenditures and projected voter turnout -- I am writing a few days before the election -- reflect this increased interest. According to one CNN report, “The 2018 Midterms will go down as the most expensive in U.S. history.” Moreover, total spending “will surpass $5.2 billion by November 6th--a 35% jump over the 2014 midterms and the largest leap in at least two decades.” Even the youngest voters, a traditionally apathetic group as a whole, have begun to care more about politics. As Olivia Paschal and Madeleine Carlisle wrote in The Atlantic, “new polling suggests that young people will vote in next week’s midterms at levels not seen in at least three decades.” Since we are so heavily invested in its outcome, it is worth examining more closely the potential implications of this year’s vote.

Looking first at the House of Representatives, the situation seems quite grim for the GOP. While they currently hold 235 seats to the Democrats’ 193 (there are several vacancies, mostly in districts they won in 2016), the Republicans have only a 15 percent chance of keeping their majority, according to FiveThirtyEight, a reputable punditry site and polling aggregator. Three main factors contribute to the Democrats’ advantage in the House: their 7.5-point lead in the generic ballot, Trump’s inability to maintain an approval rating above the low 40s as measured by polling averages (it has been below 43 percent since March), and the poor track record the party holding the presidency has in midterms.

Still, some commentators argue that Republicans have more reason for hope than these numbers initially suggest. John R. Petrocik and Daron R. Shaw, for example, contend at Sabato’s Crystal Ball (centerforpolitics.com) that neither increased turnout among liberal voters nor anti-presidential backlash will greatly benefit Democrats in the race for the House, contrary to the expectations of many. In their view, the midterms’ frequent tendency to seriously harm the president’s party results largely from that party’s success during presidential election years in winning House seats that don’t normally belong to them. Because the Republicans not only failed to gain but actually lost seats in 2016, the authors conclude, they are less likely to suffer large losses this year as, for example, the Democrats did in 2010. While their interpretation is somewhat unorthodox, other pundits such as Sean Trende of RealClearPolitics also admit that, as Trende wrote recently, “There really are believable scenarios [in which they hold the House] that don’t require Republicans to win districts that they have written off.”

However, the focus on which party will win the House ignores the power a slim majority would give either side. Even the rare accounts favorable to the GOP usually acknowledge that their current majority will shrink considerably. Trende’s scenario (he has also written a competing one in which the Democrats make large gains, for more than a slight majority) concludes that Democrats will pick up 22 seats--one short of a majority--or possibly as few as 19, which would reduce the Republican House margin by more than three-quarters. As recent congressional gridlock reveals, accomplishing legislative priorities often requires a “working majority,” not a mere numerical one. The Tax Cut and Jobs Act of 2017, for example, probably the most important conservative policy change of the Trump era, had eleven Republican dissenters in the House. Similarly, the attempted “skinny” (or partial) repeal of the Affordable Care Act passed the House by only four votes before losing in the Senate. It seems clear that even a surprisingly bad performance for Democrats would substantially enhance their capacity to block President Trump’s proposals.

At the same time, the Senate is about as bad for Democrats as the House is for Republicans. While the Democrats benefit even there from President Trump’s unpopularity, the extremely lopsided Senate map presents them with serious problems. Ten Democrats are up for re-election in states he won, while only one Republican is up in a Clinton-supporting state (Nevada). Because of Vice President Pence’s tie-breaking vote, the Democrats need a net gain of two seats to take the Senate. Their most plausible path entails winning every state with a tossup race (Nevada, Arizona, Missouri, Indiana, and Florida) and at least one where they trail significantly (North Dakota, Texas, or Tennessee).

Additionally, the Senate Republicans are likely to shift a bit to the right. Bob Corker and Jeff Flake, two of the most moderate conservatives, are retiring. With John McCain’s death and Lindsey Graham’s apparently growing loyalty to Trump, Lisa Murkowski and Susan Collins are the only senators in their party with a decent chance of siding with Democrats more than occasionally. If the Republicans gain any seats in the upper chamber, as is likely, it would allow them to continue transforming the judiciary (not just the Supreme Court, but lower courts as well) and to stop most liberal bills from even reaching Trump’s desk.

Of course, we cannot predict election results with great accuracy or certainty. Yet whether the Republicans or the Democrats celebrate on Tuesday night, we should expect the spiral of congressional paralysis to deepen for at least two more years.