President Trump's approval rating among five key voter groups shows how tough it will be for Republicans to keep control of the House in the midterm elections.

The bottom line: The most important group to watch will be the #NeverHillary independents — a group that narrowly disapproves of Trump's performance, according to a new Axios-SurveyMonkey poll. It's also not a good sign for Republicans that Trump's disapproval ratings are high among suburban white women. The other subgroups lean pretty much the way you'd expect.

What to watch: We'll be revisiting these groups and their views on different topics each week in the run-up to November's votes.

The 2018 voter groups:

1. #NeverHillary Independents are closely split on their views of Trump, and in 2016 they split three ways: 37% didn't vote at all, 33% picked Trump and 23% went for a third party candidate. The big question in 2018 is whether their disapproval of Trump will lead them to vote for a Democrat.
2. Suburban white women are a critical swing voter group. Nearly half strongly disapprove of Trump, but they're almost evenly divided between Democrats (44%) and Republicans (42%). They are mostly moderate or conservative in their views, but they care a lot about health care and immigration — two of the biggest issues that are likely to drive Democrats to the polls.
3. Rural Americans are overwhelmingly white (76%), and many love Trump (38% strongly approve). They care most about jobs and the economy, but if Republicans want their help, they'll have to address the concerns of the 42% who disapprove of Trump.
4. African-American women are often called the backbone of the Democratic Party, and not surprisingly, they overwhelmingly disapprove of President Trump. Two out of three voted for Hillary Clinton in 2016. But if Democrats want their vote in 2018, the party will need to invest in the issues they care about.
5. Millennials (18-34) don't like Trump, and they are more likely to mention education and the environment over issues like health care and immigration. In 2016, 31% voted for Clinton and 19% voted for Trump, but 39% stayed home. If Democrats want to win them over, they'll need to focus on voter registration — because millennials are the least likely group to report being registered to vote.

Go deeper:

• What Democrats need to take the Senate
• Huge majority of Republicans support Trump's Putin press conference
• Why Trump is tweeting about Michael Cohen’s taxi business

Methodology: This analysis is based on SurveyMonkey online surveys conducted between June 19 and July 20 among 52,211 adults in the United States.  Results for congressional vote preference and for subgroups based on self-reported rural, suburban or urban status are from interviews conducted July 1-13 among 9,767 adults nationwide. The modeled error estimate for the subgroups ranges between plus or minus 1.5 percentage points and plus or minus 3.5 percentage points.

Respondents for this survey were selected from the more than 2 million people who take surveys on the SurveyMonkey platform each day. Data have been weighted for age, race, sex, education, and geography using the Census Bureau’s American Community Survey to reflect the demographic composition of the United States age 18 and over. Crosstabs available here.