Susan J. Demas: I got the Michigan Democratic primary wrong. Here's how Sanders pulled it off

Bernie Sanders' victory in Michigan was the biggest electoral surprise so far of the 2016 election season. It's the kind of unbelievable, conventional-wisdom-defying upset that makes covering elections so much fun. 

And I called it wrong.

I know Michigan well. The polls were clear. Five Thirty Eight, the highly influential election analysis site, put Clinton's chances at greater than 99 percent. Most Democratic voters I talked to felt Sanders' vision was too pie-in-the-sky and Hillary Clinton was the strongest general election candidate.

I was wrong. As I said on the radio this morning, "I'm here to fall on my sword."

I wrote that his economic message wasn't resonating in Michigan. I thought his answer on the auto bailout hurt him, but that's a question mark, since exit polling didn't ask about that. Clinton won overall on jobs and the economy, but it was a close margin. And exit polls did show that Sanders' anti-free trade tirades and emphasis on income inequality helped him. He also won voters who said they were "very worried" about the economy.

The absolute polling failure, especially for robo-polls, is something we'll need to grapple with in the future. Thanks to new regulations, many of these surveys don't include cell phones. That can lead to underestimating the youth and minority vote  –– which turned out to be critical in the Democratic primary.

Now it's time for a bit of a reality check (i.e. the part Sanders supporters won't like). Because the race was close, there wasn't a big gap in delegates awarded to Sanders and Clinton. She also had a huge night in Mississippi, which means Sanders actually won fewer overall delegates last night. And Sanders is behind where he needs to be in the delegate count to win the nomination.

But Sanders' stunning victory in Michigan –– a state he wasn't supposed to win –– could give him momentum. Will that scramble the race in Ohio next week and other big delegate states? Stay tuned.

In the meantime, it will take more time to fully analyze how Sanders won the Mitten, but here are my initial observations:

• The youth vote came through for Sanders. He won 81 percent of voters 18-29, according to exit polling. Turnout was way up in the counties of Washtenaw (University of Michigan), Ingham (Michigan State University) and Kalamazoo (Western Michigan University). Now Sanders has bragging rights that he's not just turning out younger voters in small states. He can do it in big swing states.

• Outstate voters came in huge for Sanders. If you look at the map, it looks like what you'd expect for a general election when Republicans lose: Clinton was strong in Wayne, which is home to Detroit, but not strong enough. She won the suburbs (Oakland and Macomb) by paper-thin margins. Sanders cleaned up in Western and Northern Michigan –– putting up some huge margins. It sure looks like an anti-establishment message was being sent. And Clinton made a big misstep in just concentrating on cities like Detroit and Flint and thinking they would carry her over the top.

• Sanders won about 30 percent of the African-American vote, and looks to have done particularly well with younger black voters. That's much better than he's done down south, and could be a good sign for him in big states like New York, Ohio and Pennsylvania.

• As for the gender gap, Sanders was helped by winning 55 percent of men to Clinton's 43 percent (leading some credence to the #BernieBro theory, perhaps). But Clinton only won 51 percent women. Usually women are more dominant in Democratic primaries.

• Sanders started at a big deficit in Michigan and closed the gap. He's upped his ground game in big states, and got an assist from some labor muscle disenchanted with Clinton, especially on trade. It's clear Clinton took Michigan for granted. The last-minute blitz of visits from all three Clintons –– Hillary, Bill and Chelsea –– couldn't save her.

• We have an open primary in Michigan, unlike several other states. And independents broke hard for Sanders, who won 71 percent to Clinton's 28 percent. Independents were 28 percent of the Dem primary electorate. Republicans attracted a greater share to their primary –– 31 percent –– and they went for Donald Trump by 9 points. It's hard not to see that independents aren't happy with establishment candidates.*

• Clinton may have been hurt by Dems making mischief on the GOP side. Democratic crossover in the Republican primary was 7 percent, but only 3 percent of Republicans voted in the Dem primary. There's anecdotal evidence that Clinton supporters thought the Dem primary was in the bag and turned out for John Kasich as a vote for sanity (I'm sure the #NeverTrump forces will thank them). Other Dems voted for Trump or Ted Cruz because they thought they would be the easiest Republicans to beat in November. Less than 20,000 votes separated Clinton and Sanders. Could Dems crossing over made the critical difference? Perhaps.

Only 57 percent said Clinton was "honest and trustworthy" in the exits, as opposed to 80 percent who said that of Sanders. That's an indication that GOP attacks against Clinton are hurting her. Although Sanders himself hasn't personally attacked her, his supporters have, particularly on social media –– egged on by Republican powerhouse SuperPACs running ads.

•  As with other races, Clinton won voters who wanted a continuation of President Obama's policies and Sanders won 75 percent who said they wanted the next president to be more liberal. The open question is how many general election voters would agree.

* Updated, 10:53 a.m.

Susan J. Demas is Publisher and Editor of Inside Michigan Politics, a nationally acclaimed, biweekly political newsletter. Her political columns can be found at Follow her on Twitter here.