The Republican and Democratic parties have both attempted to identify the issues — immigration and the economy, respectively — that are most important to voters (other than the desire to send a message to Donald Trump). But the truly big issue, barring an unforeseen event, that will motivate the electorate will be something that neither side of the aisle is currently talking much about: Health care.

Current polling is showing that health care is topping the economy in importance for voters throughout the United States. According to a recent Reuters/Ipsos poll, health care is the most important issue for voters in the midterm elections; in an Economist/YouGov poll, 67 percent of Americans say that the economy is a very important issue, but 72 percent health care is a very important issue. Among women and independents in the same poll, 80 and 69 percent, respectively, believe that health care is very important, which is 13 and 6 points higher than those women and independents who view the economy as very important. Additionally, a January 2018 study by the American Psychological Association found two thirds of Americans cite the cost of health insurance as a major stressor in their lives.

And, poll after poll over the last several months has shown that the majority of Americans believe that the country is headed in the wrong direction, even as unemployment is near-historic lows and GDP has seen strong growth. But the Democrats are seemingly about to shift to the more strategically sound tactic of asking voters if the booming economy is personally benefiting them — and, when it comes to health care, many voters are likely to say no.

What is currently a murmur of discontent within the electorate will become a a roar before we know it: Roughly two weeks before Election Day, the 2019 premiums for Obamacare plans will be released to the public. All indicators show that, following the pattern of the last few years, consumers can expect to see double-digit rate increases in most states. But it could be even worse because the previous premium hikes came before Trump and Republicans did away with health care subsidies that helped low income Americans (in October 2017), as well as eliminated the individual mandate (in the tax reform bill passed in December 2017), which are both expected to push Obamacare premiums even higher.

And, though Obamacare premiums are not necessarily related to private insurers' plan costs, many Americans will either conflate the Obamacare premium hikes with what their own private insurance premiums will be in 2019, or worry that their private plans will experience similar, if not greater, increases.

The truly big issue, barring an unforeseen event, that will motivate the electorate will be something that neither side of the aisle is currently talking much about: Health care.

Meanwhile, in a number of states with Republican governors (some of whom are up for reelection) who passed on expanding Medicaid under the Affordable Care act, will face voters who can't qualify for Medicaid, lost their Obamacare affordability subsidies and face premium hikes. But in late July, President Trump decided to prolong making a decision on whether to allow them to expand access to Medicaid in their states, but less broadly than is required under under Obamacare. Trump reportedly opposes any type of Medicaid expansion because he believes that it would be an expansion of the Affordable Care Act.

Nonetheless, voters in Utah, Nebraska and Idaho — all of which are solidly Republican states — will be voting on fairly popular statewide ballot initiatives on Medicaid expansion. That's unlikely to benefit incumbent Republicans like Rep. Mia Love of Utah’s 4th congressional district, who is facing a tough reelection fight against Democrat Ben McAdams (who has accused her of not assisting the state in obtaining a Medicaid expansion waiver from the Trump administration).

Love's is hardly the only race in which health care has reared its head. In last March’s special election in Pennsylvania’s 18th congressional district, a solid GOP district with a R+11 spread and that President Trump won by almost 20 points, Democrat Conor Lamb pulled off an upset victory — just another in a string of upsets that Democrats have been pulling off since early 2017. Nearly two thirds of the voters who either viewed health care as the “most important” or a “very important” issue voted for Lamb.

With Tuesday’s special election in Ohio’s 12th congressional district (which Trump won by 11 points in 2016, and hasn’t elected a Democrat to Congress since 1981), Democrat Danny O’Connor is expected to finish far closer to his Republican opponent than would usually be warranted and may even win the race. He wisely tailored his main campaign theme to expanding access to and reducing the cost of health care for American families. It is likely that the majority of voters who say that health care is either the most important or a very important issue will end up backing him. Should O’Connor win the district, which Cook Political Report ranks as R+7, he almost certainly will have health care to thank for it.

One would think that the booming economy would be a boon for Republican candidates and help stem the tide of the enthusiasm among the Democratic base. However, though polls are showing that the economy is important to the electorate, voters have already demonstrated how health care is an even more important issue to them.

Republicans (if not former Trump campaign strategist Steve Bannon, who recently shrugged off these concerns) are already concerned about how they are faring with suburban, especially the suburban women who helped the GOP take the majority in the House of Representatives in 2010 and Senate in 2014. Since Trump’s election, a large enough percentage of them have moved away from the Republican Party and have voted for Democratic candidates, which helped Democrats win across the country.

Last month, the University of Delaware’s Center for Political Communication released a study that found two thirds of women in the United States are angry at the state of politics today and only 15 percent of those women say that their anger makes them less likely to vote in November. This conforms with other polls over the past year that have shown women to be incredibly angry at the way the nation is being governed and the state of politics.

Anger is the most abundant renewable energy source on the planet and Democrats are seeking to weaponize it in the midterm elections. Barring the unforeseen, health care will be the dominant issue for voters in November, just as the Obamacare premium rate hikes are released just before Election Day. This will cause voters' anger to reach new heights. Democrats may have passed Obamacare and been blamed for its myriad problems through 2017 but, with the Republican failure to change it for anything but the worse since grabbing the reins of both the White House and Congress, Democratic candidates seeking to repeal and replace Republicans are likely to benefit.

Evan Siegfried is a Republican strategist and commentator and the author of "GOP GPS: How to Find the Millennials and Urban Voters the Republican Party Needs to Survive."