The 2016 Republican primary fight has provided lots of personality clashes, but little in the way of actual accomplishment or policy substance. Donald Trump has dominated the race with taunts about Ted Cruz's wife, a continuing vendetta against Fox News anchor Megyn Kelly, and thin promises to "make America great again." And yet, he has built a significant delegate lead in the GOP steeplechase.

But will Trump's circus work in Wisconsin? We'll find out today, when Wisconsin voters go to the polls, with 42 delegates to the Republican convention on the line. But so far, at least, Wisconsin has proven difficult for Trump's rhetoric to crack. He trails Ted Cruz by several points in the Real Clear Politics polling average. And the reason why could be telling for the future of the GOP race.

Throughout the country, Trump resonates with disaffected Republicans in large part because of their frustration with unrealistic promises made by the GOP in the last two midterm elections — and the failure to deliver on these promises, especially on immigration and ObamaCare. Republican majorities in both the House and Senate failed to deliver either a repeal or defunding of ObamaCare despite myriad promises to force President Obama to cave on his signature accomplishment. The only progress on immigration came from the reviled Gang of Eight proposal that conservatives considered an amnesty program, and which sunk Marco Rubio's presidential aspirations in 2016.

But in Wisconsin, Republicans have had a much different experience over the last five years. And that could be why Trump's attacks on the establishment have not generated the same enthusiasm in Wisconsin that they have elsewhere.

Badger State voters elected Scott Walker as governor and a Republican-controlled legislature in 2010, and these conservative lawmakers wasted no time in making good on their promises. They passed reforms on public-employee unions to prevent a budget crisis and to undercut the political power of Big Labor in the state. That reform alone saved Wisconsin taxpayers over $5 billion in the years since. Walker and the GOP also passed a voter ID law that has held up in the courts, and passed right-to-work legislation. Walker has managed to pass balanced budgets without raising taxes, too, another issue on which the grassroots and so-called "establishment" see eye to eye. It was this track record of accomplishment that allowed Walker to be the first governor in U.S. history to withstand a recall election, easily beating back the attempt to remove him from office, and led to his re-election two years later.

Trump came into Wisconsin attacking Walker, mainly because Walker had repeatedly criticized Trump earlier in the campaign. (Walker has endorsed Cruz.) Strangely, Trump attacked Walker for not raising taxes and for not cooperating more with Democrats, arguments that left Wisconsin Republicans scratching their heads. The attacks backfired, and Cruz quickly rose in polling. Trump later reversed himself on Walker, but the episode highlighted a big problem in Trump's campaign. Team Trump just assumed that his national anti-establishment message (and usual pattern of personal attacks) would work in Wisconsin. Trump and his team clearly didn't bother to learn anything about the voters in these communities first.

In researching my upcoming book Going Red, and speaking with numerous people in key swing states and counties, it became clear that this specific failure — national messaging and a neglected organizational game — doomed Republicans in the 2012 election as well. Wisconsin served as a proving ground for the ability of Republicans to win hard-fought elections by driving turnout on their own terms, by knowing their constituencies and expanding them with repeated voter contact. These are lessons the national GOP still needs to learn.

Scott Walker's success in winning two terms as governor and beating a recall in between serves as a marker for Republican success in Wisconsin. Not only did Walker win the office, he made significant and controversial changes, and then won again and kept the GOP's legislative majority in doing so. How did that happen? Walker himself spelled it out at the RedState Gathering in August 2015, in a meeting with Salem Media Group journalists and pundits.

"Between 2012's recall and 2014's reelection, we spent four times more money on digital than we did two years ago," Walker explains when asked how he would approach the 2016 presidential election. "Why? Because when we contacted twice, we had twice as many personal contacts with voters in '14 as we did in '12. Even though we broke the record in '12 two years earlier."

Walker stresses that Obama's use of Facebook and other social media was not an end unto itself. "President Obama's big deal wasn't just that he used digital as though it was magically Facebook and Twitter," Walker says. "They used digital to recruit and inform real people, who then talked to their neighbors. They talked to people they worked with. They talked to people they go to church with. The primary system is going to be driven by that," Walker predicts, "and so will the nominee" in the general election.

The other proven winner in Brown County and eastern Wisconsin, Reid Ribble, has advice for whoever wins the Republican nomination. "Genuineness and humility matters," he says. "There are some very traditional values that are held dearly in northeast Wisconsin, in Brown County, and genuineness and humility count," he emphasizes. [Going Red]

Today's Wisconsin primary will demonstrate how well the Trump and Cruz campaigns learned those lessons. Who has taken the time to get to know Wisconsin voters, know what makes them tick, communicate with them, and make them feel valued? That candidate will emerge as the winner of the primary tonight, and might provide a better look at the potential for competitiveness in other swing states, too.

And spoiler alert: It does not look like that candidate is Donald Trump.