That gavel’s so close, she can almost feel it. Photo: Win McNamee/Getty Images

On October 24, 2016, Hillary Clinton led Donald Trump in national polls by an average of 5.5 percent. A little over a week later, that figure was just 2.2.

Two major events happened in the interim: James Comey released his infamous letter, revealing the discovery of new emails related to the FBI’s investigation of Clinton — and the Department of Health and Human Services announced that premiums on Obamacare’s benchmark plans were set to skyrocket by an average of 22 percent in 2017.

Postmortems of the 2016 campaign have placed a great deal of emphasis on the former development. But there’s some evidence that the health-insurance news was just as (if not more) damaging to Clinton’s cause. In a working paper released last year, Ohio State University political scientists Vladimir Kogan and Thomas Wood found that, at both the county and individual levels, support for Trump was correlated with rising premiums among those who purchased their own health insurance (as opposed to receiving it through an employer or Medicare). The fact that the vast majority of Obamacare enrollees were shielded from premium hikes by federal subsidies did not prevent Democrats from paying a political price. Nor, for the matter, did the reality that congressional Republicans had deliberately undermined the Obamacare marketplaces in myriad ways. A Democrat was in the White House. Headlines heralded a giant spike in the cost of health insurance. And some tiny — but theoretically significant — fraction of the electorate turned rightward in disgust.

And yet, if soaring Obamacare premiums cost Democrats the presidency in 2016, they just might give Team Blue the House this November.

Donald Trump spent much of his first year in office trying to make Americans’ health insurance more expensive. In interviews with major publications last spring, the president repeatedly threatened to deliberately destabilize the Affordable Care Act marketplaces by abruptly halting subsidies to insurers. By year’s end, he had made good on that threat. Meanwhile, his Health Department cut funding for the law’s outreach groups; slashed Obamacare’s advertising budget by 90 percent; spent a portion of the remaining ad budget on propaganda calling for the law’s repeal; cut the open-enrollment period by 45 days; announced that it would be taking healthcare.gov (where people can enroll in Obamacare online) offline nearly every Sunday during that time period for “maintenance” purposes; described Obamacare as “a bad deal” that Americans “won’t be convinced to sign up for” in official public statements; and expanded access to “short-term” health plans that do not meet Obamacare’s benefits requirements (and thus, are useless to anyone with a preexisting conditions, or who develops a serious condition after purchasing the insurance). Oh, and just before Christmas, congressional Republicans killed Obamacare’s individual mandate.

Experts expect all of these measures to depress participation in Obamacare, especially among the young and the healthy, thereby forcing insurers on the ACA marketplaces to jack up their premiums. A recent study from the nonpartisan Urban Institute projects that Trump’s acts of sabotage are poised to single-handedly generate an 18 percent increase in premiums in 2019; once one factors in secular increases in health-care costs, the headline number is likely to be even higher.

The implications of Trump’s sabotage weren’t lost on all Republicans. Susan Collins famously refused to vote for abolishing the individual mandate — until Mitch McConnell “promised” that he would prioritize legislation stabilizing the Affordable Care Act afterward. But last week, efforts to add stabilization funds to the omnibus spending bill collapsed, as Republicans insisted on pairing those appropriations with abortion restrictions. The omnibus was the last, best chance for Congress to fortify the individual insurance market before Election Day. It is now all but certain that insurers will announce giant premium hikes in late October — and this time, the GOP is poised to pay the price.

The public has always tended to blame the president’s party for anything bad that happens on his watch. Trump has has tried mightily (if clumsily) to make Obamacare an exception to this rule — repeating, over and over, that Democrats would “own” any future problems the law encountered. The president has even gone so far as to claim that Barack Obama purposely designed the ACA marketplaces to self-destruct shortly after he left office.

Voters aren’t buying it. Polling from the Kaiser Family Foundation (KFF) has consistently found that most Americans believe Trump and his party are responsible for any future problems with Obamacare. As of late last year, 61 percent of voters told KFF that they would blame Trump and the GOP for such problems, while just 37 percent said the buck stopped with Obama.

Those numbers reflect the Democratic Party’s broader advantage on the issue of health care. As of last October, 50 percent of voters said that Democrats would do a better job of handling health care than Republicans would, while just 32 percent said the opposite, according to polling from Pew Research Center. That lopsided advantage persists across surveys, and it isn’t hard to see why: The GOP’s Obamacare replacement bill was the least popular piece of major legislation in modern American history. Plenty of voters had disapproved of Obamacare, but very few wished to see it replaced with the Republican alternative — a law that retained all of the ACA’s bureaucratic complexity, while shrinking its insurance subsidies, slashing Medicaid, and plowing the consequent savings into a capital gains tax cut for millionaire investors.

Thus, the more prominent questions of health-care policy are on Election Day, the more seats the GOP is likely to lose. Republicans want swing voters to be thinking about the strength of the “Trump economy” when they cast their ballots, or else, the threat of MS-13 . Any development that diverts the public’s attention to health care — and thus, to the two parties’ disparate fiscal priorities — is likely to redound to the Democrats’ benefit.

The rising cost of health care is already a top issue for 2018 voters. And Democrats have already won improbable victories by campaigning on it: Conor Lamb railed against the Republican health-care bill, and Paul Ryan’s broader austerity agenda, while successfully seeking election in a district that had backed Trump by 20 points. A survey from Public Policy Polling found that 52 percent of voters in the PA-18 special election named “health care” as one of their biggest concerns — and 64 percent of those who picked as their No. 1 issue broke for Lamb.

And a giant spike in premiums — on the eve of November’s elections — would (almost certainly) make health care an even more salient concern for the electorate than it is today. Which is to say: Through his myriad acts of Obamacare sabotage, Trump may well have provided Democrats with a perfect October “surprise.”