It’s widely assumed that President Trump will have a good shot at winning reelection if he hangs on to only one of the three “blue wall” states he cracked: Wisconsin. And Wisconsin will be brutally close -- even if Pennsylvania and Michigan are not.

After all, in 2018 Democrats racked up big statewide wins in those latter two, suggesting they might be shifting back to their more Democratic orientation. But Wisconsin governor Tony Evers ousted notorious union-busting Republican Scott Walker by barely more than one point.

Trump snatched Wisconsin by barely more than 22,000 votes. Barack Obama won the state by large margins in 2012 and in 2008 -- but this disguises just how closely fought the state has historically been. And its outsize percentage of non-college educated whites makes it ripe for Trump to hold.

A new poll from the Upshot and Siena College finds the contests to be incredibly close in Wisconsin and 5 other swing states, stirring a fresh round of hand-wringing among Democrats.

I spoke to Ben Wikler, the state Democratic Party chair in Wisconsin, about what Democrats need to do this time. A lightly edited and condensed version of our conversation follows:

Plum Line: The new Upshot poll has it very close in Wisconsin. It shows Joe Biden up 3, Bernie Sanders up 2, and Elizabeth Warren even. How close is this to the mark?

Wikler: The margin of victory for the presidential campaign in Wisconsin was under 1 percent in 3 of the last 5 presidential elections. No one should be under any illusion. It’s balanced on a knife’s edge.

What’s your analysis of the likely electorate?

Historically, it has been 57 percent white voters without a college education. That’s more than Michigan (51 percent). The percentage of voters of color is somewhere between 6 and 9 percent. Research about Barack Obama’s victory has found that he did a lot better with working class white voters than exit polls suggested.

Why did Obama do so much better than Hillary Clinton among them?

Part of 2008 was the historic economic meltdown, and Obama was running for change.

Something that a lot of observers missed in 2016 is that there was a regional recession in the Midwest, especially in manufacturing. Voters wanted change once again.

There’s another manufacturing recession happening in Wisconsin, Pennsylvania, and Michigan right now. That creates ripe conditions for a change vote.

Another piece of this is that there was a very deliberate effort to suppress votes in Wisconsin in 2016, which stretches back to Walker entering office. There’s a body of political science literature about the impact of smashing labor unions on increasing Republican vote share.

On top of that, Republicans have pushed through a harshly punitive voter ID law, and a string of other changes, including making it far harder to organize and register voters.

What can we learn from Hillary’s loss that can’t be blamed on other factors?

The Clinton campaign started to build the field operation late. The single biggest thing we learned is you have to start early. My predecessor as state party chair hired our statewide organizing director in the spring of 2017, and had hundreds on the ground by the fall of 2018.

That field effort more than made up the governor’s 1.1 point victory in 2018. We’ve kept our foot fully clamped on the accelerator ever since then.

What else has to happen to win there? Where does the ground have to be made up?

Democrats have to organize across every community to win — in rural areas where Democrats sometimes don’t show up.

Trump racked up massive margins in 2016 in rural Wisconsin. Now he has a record to flee from. Communities have been shattered by the farm crisis, which has been exacerbated by his trade policies. There’s an opening for Democrats — even if we don’t win majorities in every rural community — to really shrink Trump’s margins. That makes it very difficult for him to win.

Suburbs are another key battleground. Trump under-performed in the counties surrounding Milwaukee. They’ve historically been deep red. Unfortunately for Trump, they keep getting bluer. Trump’s personal affect and policies have been repellent for those areas.

Minority turnout is the final piece?

The final piece is cities — especially organizing in communities of color. All the factors I mentioned helped drive down turnout in Milwaukee. There are organizers with extraordinary skills and deep roots in the community who are knocking on doors — right now — in Milwaukee to change things in this cycle. A lot of that infrastructure wasn’t in place in 2016.

Frank Wilkinson of Bloomberg recently floated the idea that there may be still more rural and non-college whites there who didn’t come out in 2016. How worried are you that we still don’t know how deep that current runs?

The potential universe in 2020 is probably a lot bigger. There’s enormous head room on both sides.

Is that worrisome?

Absolutely! Trump has some profound cracks in his base, but he’s also flooding the state with resources to find his voters. We know this is going to be an enormous battle.

The Biden argument is that he’ll do better with blue collar whites because he has a connection to the middle class. The Sanders-Warren argument is that a full throated populist message that treats the system as rigged the way Trump did — only in a non-fraudulent way — is the way to cut into those margins among rural and non-college whites. Where do you come down?

There’s a path for any of our Democrats to win in Wisconsin. The specific path probably varies slightly, depending on which one is running.

The uniting factors for victory in Wisconsin tend to involve showing up everywhere — often — and listening with authenticity. That’s a recipe that’s available to any of our candidates.