(CNN) The biggest 2020 news this week is not the end of special counsel Robert Mueller's Russia investigation. It's that President Donald Trump's administration has asserted for the first time that the entire Affordable Care Act should be struck down .

Health care has consistently been listed by voters as a top issue to their vote. A CNN poll taken this month found that health care was already ranked fourth when Americans were asked what the most important issue was related to their 2020 vote. Compare that to Mueller's probe, which 0 respondents said was the most important related to their 2020 vote.

I would expect health care's importance to 2020 voters to go up in the coming weeks and months. When health care has been in the news previously during the Trump administration, its importance to voters has risen. We saw this during the failed ACA repeals in mid-2017 . And we saw Democratic candidates focus on it during the 2018 midterms as well.

Health care was a driving factor in the midterms. When likely voters were asked just before Election Day how important an issue was to their vote, a higher percentage (52%) said health care than any other issue. In that same poll, the Russia investigation ranked as the least important of the eight issues asked about.

The topic of health care almost certainly helped the Democratic Party last year in its bid to retake the US House. Poll after poll showed that Democrats were more trusted than Republicans on health care. An ABC News/Washington Post poll conducted just before the election found that voters trusted Democrats over Republicans by a 16-point margin on handling health care. That was the largest gap in favor of the Democrats of any issue that was ranked highly important by a lot of voters.

In the national exit poll , health care was listed as the most important issue by more voters than any four issues asked. Among those who said it was most important, Democrats won a 75% to 23% majority.

Looking ahead to 2020, health care could help Democrats if it becomes a referendum on the ACA (i.e. Obamacare).

The ACA remains popular with Americans. In the latest Kaiser Family Foundation poll out Tuesday, the ACA scores a 49% favorable rating to a 42% unfavorable rating among voters. This is very similar to the split when voters gave House control to the Democrats last November. It's also about the same when then-Sen. John McCain infamously gave his thumbs-down to end Republican hopes of repealing parts of the ACA in the summer of 2017.

Indeed, that failed repeal attempt demonstrates the potential pitfall for Trump of going hard after the ACA. While almost nothing has moved his approval ratings, health care has. When ACA repeal was debated (and failed) in 2017, Trump's approval rating among voters dropped to its all time low of 37% in the FiveThirtyEight aggregate . The 22-month-long Mueller investigation never had that effect on Trump's ratings.

Still, health care is not automatically a win for Democrats. Republicans may hope to change the topic from the ACA to health care at large. A number of prominent Democrats are currently discussing switching over to a "Medicare for All" system , which would create a universal coverage program run by the federal government. If that plan includes getting rid of private insurers, then it could hurt Democrats. Although Medicare for All polls well in the abstract, a January Kaiser Family Foundation poll found that 58% of Americans were opposed to a system that eliminates private insurers.

Democrats will certainly be forced to reckon with Medicare for All in their 2020 primary. Kaiser has been asking for the past year-and-a-half whether congressional Democrats should concentrate on "improving and protecting" the ACA or passing Medicare for All. Previously, more Democrats than not preferred that their party concentrates on "improving and protecting" the ACA. In the latest Kaiser poll, more Democrats now prefer concentrating on going for Medicare for All..

About the only guarantee is that the most recent move by the Trump administration to end the ACA moves health care back into the spotlight. We've already seen that the party who seeks to end the status quo on health care has lost their majority in 2010 (Democrats) and 2018 (Republicans). The side that is seen as mostly likely to defend the status quo on health care in 2020 is likely to benefit from it. It's not necessarily clear who that will be at that this point, given that options range from ending the ACA to implementing Medicare for All. It's really all about how the parties play their cards.