Ten years ago, the progressive writer Thomas Frank wrote What’s the Matter With Kansas?, a runaway best seller, and a few months after its publication, when George W. Bush won reelection, the book seemed to explain what had happened. Frank set out to resolve the paradox that befuddled liberals: Why did so many white Americans of modest means in the heartland embrace a party in thrall to the ultrawealthy?

Frank audaciously proposed that Democrats address their catastrophic standing in Kansas, and places like it, not by moving toward the center but away from it, by embracing populist economics. Even more audaciously, he proposed that his stratagem might actually make the party competitive in a state Republicans always win by landslide margins.

Now, shockingly, Frank’s outlandishly hopeful vision stands on the verge of coming true. Voters in ultra-Republican Kansas have risen in disgust against their eternal party. Independent Greg Orman is running ahead of Pat Roberts, the longtime Republican incumbent senator, and, according to a poll last week, is attracting upwards of 30 percent of the Republican vote. Paul Davis, an honest-to-God Democrat, is leading Governor Sam Brownback in most polls. Interestingly, however, none of this is happening as a result of the left-wing populist turn Frank urged. In fact, as much as Kansas provides liberals a happy story line in an otherwise difficult campaign season, it also offers a lesson that might give progressive Democrats pause.

The cause of all the trouble for the Republicans is Brownback. Sam Brownback is not some random shmoe who stumbled onto the party ticket and proceeded to say something offensive about rape or evolution. Brownback comes from deep within the party bosom, first as a prominent member of the revolutionary House Republican class of ’94, then senator (he hired Paul Ryan as his legislative director), and since 2011, governor.

He has centered his governorship on a plan to phase out the state’s income taxes. Over and over, Brownback held up Kansas as a proving ground for the proposition that cutting taxes for the affluent would unleash prosperity. Opponents warned the plan would wreak havoc on the state budget; Brownback and his supporters, including influential national Republican policy-makers like Arthur Laffer and Stephen Moore, insisted no such thing could happen. “We believe this is a strategy that builds a strong state in the future on the red-state model,” the governor boasted as recently as February. “Brownback,” reported National Review, “intends to make his state a showcase for the country.” Awed by his display of ideological resolution, figures like Grover Norquist and Bill Kristol touted Brownback as a potential 2016 contender.

Brownback’s program has failed every practical test. The state budget is hemorrhaging revenue, even after making up some of the funds lost on tax cuts for the affluent by jacking up taxes on the poor. Since Brownback’s cuts took effect, job growth in Kansas has lagged behind the national level and behind all but one of its neighboring states. Brownback’s spectacular belly flop was hardly a novel event; the same thing happened when George W. Bush enacted sweeping tax cuts for the rich. Nor was there anything novel in Brownback’s approach to the grumblings of mainstream Republicans in the state senate, whom he dispatched by launching primary challenges against 11 of them in 2012, of which only two survived. Remnants of the old-line party formed a splinter group, Traditional Republicans for Common Sense, denouncing Brownback. Even as moderate Republicans were openly organizing against him, though, he continued to assume, not without basis, that the dissent would come to nothing in the end.

Indeed, the ineffectual bleats of the doomed intraparty dissidents were all part of the script. “We had a three-party system here, with Democrats and liberal Republicans forming a parliamentary majority that consistently voted for more taxes and bigger government,” he told National Review last October. In February, after serious dissent had already broken out among Kansas Republicans over Brownback’s obvious voodoo math, a pollster of his told the Times that President Obama’s approval ratings, in the mid-30s in the state, would render Brownback all but invulnerable. Brownback held the party, and the party held the state.

This was a perfectly sound assumption in an age of polarization. Nearly all of America has hardened into red and blue strongholds, united by mutually irreconcilable philosophical and cultural mores, and frequently imbibing news hand-picked from their own team. Brownback, like so many politicians, seemed to reside in what is known in the political trade as dead-girl/live-boy territory.

But the moderate Republican defectors haven’t faded away. Large chunks of what Brownback called the third party—“liberal Republicans”—have joined with the second party. Panic at this development has spread from Kansas to the precincts of Republican Washington. Moore sent an op-ed to Kansas newspapers claiming the governor’s program had worked. (He cited job-growth figures starting five years before the tax cuts took effect, and which were, in addition to being therefore irrelevant, wildly incorrect.) Wall Street Journal columnist Kimberley Strassel recently insisted that Brownback’s program is faring just fine, mustering a level of denial that sounded almost as if she were a conservative mother who has just caught her son making out with his buddy. “Kansas hasn’t turned against conservatism,” she wrote, “it’s just mired in a messy and confusing political environment.” Kansans are just confused. Dad will slip them a copy of the latest Ann Coulter, and that will straighten them out.

The sudden jeopardy to Pat Robert’s once ultrasafe Senate seat is now collateral damage, and to the question that has so vexed liberals (and centrists) for the last decade—is there anything elected Republicans can do that is too extreme or incompetent for their own base?—the answer may at last be “Yes.” But conspicuously absent from this shift has been the Democratic Party. The Democratic candidate for Senate, Chad Taylor, has ended his campaign, bowing to the reality that he was much less attractive to voters than the independent candidate. Davis is running a safe, boring campaign; the same recent poll that found him leading Brownback by four points also found that 35 percent of voters have no opinion about him at all.

The Thomas Frank vision, of a fighting populist Democratic Party prying working-class whites from the Republican Party with blunt appeals to economic populism, bears almost no resemblance to the events in Kansas. Mostly, liberals have benefited from right-wing self-destruction. To the extent that they have a deliberate strategy, the Democrats are attempting essentially the opposite of Frank’s ­prescription—they are trying to cobble together their base with the traditional, Bob Dole fiscal conservatives. Dole, the iconic Kansas postwar Republican, ridiculed and resisted the wave of supply-side economics when it appeared in the 1980s. Ultimately he gave in and ran for president in 1996 promising sweeping, budget-busting tax cuts like those Brownback has enacted. The old Dole’s brand of fiscal ­conservatism—or the Eisenhower brand, to cite another Kansan—seemed to have expired, but it is taking its vengeance from beyond the political grave.

Brownback’s biggest mistake was to forget a lesson Frank made well: Even in Kansas, tea-party populism requires the maintenance of a ruse. One needs cultural elites and other enemies to bash in broad daylight while doing the dark work of plutocracy behind the scenes. Openly conducting class warfare on behalf of the rich is no way for a pseudo populist to get ahead.

“We have a red-state model and a blue-state model,” explained Brownback last year, “It’s going to break one way or the other. One will win and migrate to Washington.” At the time he said it, this was a boast. Now it sounds more like a warning.

*This article appears in the September 22, 2014 issue of New York Magazine.