Unions and national progressive groups went some distance to nationalize the Chicago campaign by aggressively backing Emanuel's opponent: Lessons From Chicago for Clinton’s Candidacy - Mayor Rahm Emanuel’s runoff-election victory could provide insight into how to woo progressives in 2016

Gerald Seib writes in The Wall Street Journal:

Hillary Clinton’s nascent presidential campaign is billed as a test of how the Democratic Party’s centrist, establishment machine will do in pacifying a progressive wing unhappy with her ties to financial interests and hungry for some alternative.

In fact, a test of that very struggle was conducted just this month. The setting was the mayor’s race in Chicago, where incumbent Rahm Emanuel—veteran of Bill Clinton’s presidential campaigns and White House, and inheritor of the Clinton family’s inclination to build bridges to the financial community—was challenged by an unabashed liberal, Jesus “Chuy” Garcia, a Cook County commissioner.

Like Mrs. Clinton, Mr. Emanuel was the object of deep skepticism on his party’s left—a skepticism that in his case ranged up to outright hostility. The skepticism was born both of what he had done and what he had failed to do while in office. On top of substantive disputes, his record of maintaining good ties—and a hefty donor base—among Chicago’s business and financial leaders was seen as both a sign and cause of misplaced priorities.

Unlike Mrs. Clinton thus far, Mr. Emanuel also faced a real, live opponent, who became the vessel for all that progressive angst and anger.

Result? Mr. Emanuel won easily, 56% to 44%, in a runoff election on April 7. He won the white vote handily but also every African-American ward in the city, despite intense unhappiness there over his closure of almost 50 schools. He won in wards heavily represented by officers of the police and fire departments, despite intense controversy over reductions in city pension programs that are running deep in the red. He didn’t win the Hispanic vote, but, while running one-on-one against a Latino foe, won nearly the same share as four years earlier.

How did he do it? In part by running as a kind of modified progressive, one who embraced the same priorities as his party’s liberal wing but with policies moderated enough to prevent scaring off moderates and business interests who would consider a more strident progressive agenda a declaration of class warfare.

In essence, Mr. Emanuel’s pitch was that he was offering working-class, poor and minority voters programs that improved their chances of succeeding without breaking the bank in the process. He terms it a choice between “opportunity-based progressivism” and the liberal wing’s “class-based, resentment-based progressivism.”

There are limits to how much of this story applies to a national presidential campaign, of course. David Axelrod, a friend of Mr. Emanuel’s and a longtime Chicago political operative, cautions that it’s easy to overstate the parallels between a mayor’s race and a national political debate. Mayoral elections tend to be more focused on personalities, competence and local issues than on ideology. “Most Chicagoans were basically measuring these guys as mayors,” Mr. Axelrod says.

Still, unions and national progressive groups went some distance to nationalize the Chicago campaign by aggressively backing Mr. Garcia and seeking to upend Mr. Emanuel. Certainly the mayor was highly vulnerable to attacks from the left. That was largely because of the anger stirred up by his decision to deal with a budget crisis by closing schools, many in African-American communities, and his decision to push for a longer school day. Those moves put him at odds with minority leaders and powerful teacher unions, a spat that became bitterly personal and led to a brief teacher strike.

That alone was enough to set a fire, but additional kindling came from Mr. Emanuel’s famously cozy relations with the moneyed interests of downtown Chicago, and his equally famously abrasive personality. Put it all together and you had the formula for a center-vs.-left conflagration.

Mr. Emanuel tried to douse it by crafting his own version of his progressive credentials, trying to show he embraced the same goals as the movement but with more achievable tactics for moving toward them. He raised the city’s minimum wage (though not as much as progressives wanted). He provided universal full-day kindergarten (though not the universal all-day prekindergarten some wanted).

He also tried to counter the perception that in closing elementary and secondary schools he had undercut his city’s poor and minority students. He did so by emphasizing a different education initiative: a program to waive community college costs for city high school graduates with a B average, a program especially beneficial for minority students.

It worked, in the sense that Mr. Emanuel won with relative ease after an early scare.

For Mrs. Clinton, the lesson may be that it is possible to craft a progressive narrative that is different from, though not necessarily at odds with, the one pushed by those who would rather have Sen. Elizabeth Warren running. Chicago shows Mrs. Clinton ignores Democrats’ new energy on the left at her peril; less clear is whether she, more than Mr. Emanuel, can find a way to actually channel it.