In Wisconsin, where Sanders and Clinton debate Thursday night, there’s a simple shorthand for the contrast in their coalitions: Madison vs. Milwaukee.

The Wisconsin Voter The Journal Sentinel's Craig Gilbert explores political trends in a purple state and beyond. SHARE Click image to enlarge.

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Nashua, N.H. — Two different Democratic coalitions are lining up behind Hillary Clinton and Bernie Sanders in this state and elsewhere.

Sanders does better with the young, the secular, the very liberal and men.

Clinton does better with women, older voters, moderates and African-Americans.

These patterns left their stamp on the Iowa caucuses last Monday. They'll help determine New Hampshire's presidential primary Tuesday.

And because each state has a different population mix, they'll influence the Democratic race in every contest ahead, including the April 5 Wisconsin primary.

In Wisconsin, where Sanders and Clinton debate Thursday night, there's a simple shorthand for the contrast in their coalitions: Madison vs. Milwaukee.

Sanders' demographic and political strengths within the party are tailor-made for one of state's two big Democratic hubs (Madison), and Clinton's strengths are tailor-made for the other (Milwaukee).

"I've always said demographics aren't destiny," Clinton strategist Joel Benenson told reporters here Friday.

"You can't take any of these states or any voters for granted, or assume these patterns play out state by state. But if you look at them as they line up, I think some of these (states) are going to pose challenges for (Sanders), some challenges for us," said Benenson, who worked for President Barack Obama's campaign in 2008 and 2012.

These fault lines do not represent warring factions in the party, at least for now. In New Hampshire, both candidates have very positive ratings from Democrats. The same is true in Wisconsin. But they do reflect competing views about the party's direction.

For a deeper look at these patterns, we examined national surveys and statewide polls in Iowa, New Hampshire and Wisconsin. Six months of Wisconsin polling by the Marquette University Law School was pooled to provide more detail about the Sanders and Clinton coalitions.

Most of the Wisconsin numbers in this story understate Sanders' support because they combine surveys from the second half of 2015, when he trailed Clinton in Wisconsin by 10 or 12 points, with the 2016 polling, in which the two are roughly tied. But the focus here is on the fault lines themselves, which have been consistent over time. (The breakdowns below for different voting groups in Wisconsin refer only to Democrats and Democratic-leaning independents, not to all voters):

Gender. In Iowa last week, Clinton won women by 9 points and Sanders won men by 8. A persistent gender gap in the Democratic race may have more to do with attitudes toward Clinton than with attitudes toward Sanders. In the Wisconsin polling, there's not much difference in how Democratic women and Democratic men view Sanders, the senator from Vermont. But there is a real gap in how they view Clinton. Clinton's positive rating among women is 10 points higher than it is among men (76% vs. 66%) and her negative rating is 10 points lower (14% vs. 24%).

Age. This has become a signature fault line in the race, as it was between Clinton and Obama in the Democratic primaries eight years ago. The age gap in Iowa was staggering: Sanders won voters under 30 by 70 points and Clinton won voters 65 and over by more than 40 points. The age gap is almost as big in Marquette's last poll. It's one reason Sanders has been leading in Wisconsin among unmarried men, while Clinton has been leading among married men.

But here are two things to keep in mind about the age gap.

First, in some polls, it's bigger among men than among women. In the Wisconsin polling, Sanders has averaged a more than 50-point lead among men under the age of 30. But his lead among women under 30 has averaged just 10 points. Young women, while they favor Sanders, still give Clinton very positive ratings. But young men are a different story. They are much more divided in their views of Clinton and their support for Sanders is overwhelming.

"So much is written about Clinton's trouble with young women," said Charles Franklin, who conducts the Marquette poll and provided the Wisconsin data used here. "But those women are supporting her at noticeably higher rates (than) young men. Age is driving them to Sanders, but gender is driving them to Clinton. There's a balancing act between these two forces."

A second point is that the age gap works both ways. The flip side of Clinton's disadvantage with young Democrats is her very large advantage with older Democrats. Clinton does well against Sanders with both sexes among older voters. And these voters matter because they turn out. In Iowa, there were many more voters 65 and over than voters under 30.

Ideology. Clinton does better with more moderate Democrats, Sanders with the most liberal Democrats. It's not that staunch liberals are hostile to Clinton. But they're crazy about Sanders. In Marquette's polling, 82% of "very liberal" Democrats have a favorable view of Sanders and only 3% have an unfavorable view.

The more liberal you are, the more likely you are to have an opinion of Sanders and that opinion is almost guaranteed to be positive. Less liberal voters don't know Sanders nearly as well.

"One of the (questions) for Sanders is, as he gets better known among non-liberal voters ... will their ideology make them less predisposed to support him?" Franklin said.

Partisan affiliation is another political fault line in the race. Clinton does better with partisan Democrats, Sanders with independents.

Church attendance. Clinton has enjoyed double-digit leads in Wisconsin among people who go to church with any frequency, while Sanders has led among those who seldom or never attend church. In a New Hampshire poll by NBC News, The Wall Street Journal and Marist, Clinton and Sanders were roughly tied with Democrats who practice a religion, but Sanders led by almost 30 points among those who don't.

Race. Clinton dominates the national polling among African-American voters, while white Democrats are much more divided. Neither Iowa nor New Hampshire has many African-American voters, a big help to Sanders, but that changes dramatically in the South Carolina primary Feb. 27. The large role the African-American vote plays in Democratic politics in many states may be the single greatest barrier that Sanders must overcome in his bid for the nomination.

In Marquette's Wisconsin polling, Clinton's numbers among black Democrats are superlative: roughly 90% have a positive view of her, hardly any have a negative view, and she dominates the matchup with Sanders, who isn't nearly as well known with African-Americans as he is with white voters.

Region. In Wisconsin, the byproduct of these political and demographic fault lines is a regional one. The Madison TV market is the only part of the state where Sanders has enjoyed a clear edge over Clinton in recent months, boosted by his strength among young and very liberal voters. But in the city of Milwaukee, Clinton has led Sanders by an average of more than 30 points, reflecting her strength among African-Americans and older and more moderate white Democrats. It made perfect sense that Sanders' first Wisconsin stop last year was Madison and Clinton's was Milwaukee.

The polling numbers reflect "divisions on age and ideology, especially, and race to some extent, and how that's embedded in our geography," Franklin said. "You see it dividing up right along I-94 between the state's two strong Democratic bastions."

Those two areas alone won't determine the outcome of the Wisconsin primary if the race is still going strong in April. "There rest of the state really does matter," Franklin said.

But they do symbolize the Democrats' two different and offsetting coalitions in the party. In Marquette's January poll, Clinton and Sanders were just 2 points apart in Wisconsin.

"If nothing changes between now and April, we're very much a state that (Sanders) has a chance to win," Franklin said. "The caveat is by April, he should be vastly better known in the state than he is now. The question is, does that help him or hurt him statewide?"

In New Hampshire, the Democratic electorate favors Sanders in ways that go beyond any "local" advantage he may have as a fellow New Englander. It's very white, very secular and very liberal. And the state's primary is open to independents.

That's why Sanders has enjoyed a sizable lead in the polls, is favored to win and cannot afford to lose on Tuesday.