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If this week was a canary in the coal mine for Wisconsin Republicans, they better learn bird CPR pretty quick.

Before Tuesday night, the state's 10th Senate District had been represented by Republican Sheila Harsdorf for 17 years, with Harsdorf winning it over her Democratic challenger by 26 percentage points in 2016. (Full disclosure: I was a legislative aide for Harsdorf between 2001 and 2007.)

Thus, when Harsdorf left her seat, it seemed as if Republicans had little to worry about; even though the incumbent was popular and outperformed the western Wisconsin district's GOP baseline, the district still enjoyed about an eight-point Republican advantage. In 2016, Donald Trump won the district by double-digits.

But when the results came in, Democrat Patty Schachtner had won the district by 10 percentage points over Republican Adam Jarchow, a state representative from Balsam Lake. It was a result that had to shock even the most pro-Democratic observers.

More important than the single seat (Republicans still hold a majority in the state Senate) is what the race portends for other Republicans in the November elections.

The deep division within the party can be seen in Tuesday's results. Jarchow performed ably in rural, working-class areas of the district that would typically be known as "Trump country." These are small towns such as Milltown in Polk County, a poor, blue-collar area that leaned Democratic until Donald Trump hit the national scene.

But it was a Republican bloodbath in the wealthier, more conservative areas of the district that border Minnesota on the West. While Waukesha County is frequently pegged as the conservative power base in the state, St. Croix County is quickly on its way to becoming the Waukesha County of the west. Many Twin Cities conservatives, fed up with Minnesota's high taxes, have flooded across the border and settled near the St. Croix River in areas like Hudson and River Falls, making St. Croix County the fastest growing county in Wisconsin between 2000 and 2010.

When Harsdorf took office in 2001, the district was evenly split between Republicans and Democrats, but within a decade, all the Twin Cities transplants had turned the district red. In 2012, while losing Wisconsin by seven percentage points, Republican presidential candidate Mitt Romney still won St. Croix County by 12 points. Just a little more than a year ago, Trump won the county by nearly 19%.

But the love affair with Trump, it seems, is over. In the wealthier, college-educated areas of the district, Republicans hemorrhaged votes. Jarchow underperformed Harsdorf by more than 20% in higher-income suburban areas, such as the towns of Hudson and Troy, and ended up losing St. Croix County altogether - an inconceivable result just days ago.

It's only one special election, and different forces are in play in any local campaign. But the gaping divide between working class and wealthy, educated voters has to shock Republicans. (As Gov. Scott Walker urged frantically on Tuesday night, it should serve as a "WAKE UP CALL" for the right.)

And it wasn't as if the "Return of the Reputables" was quarantined on the western side of the state. A Democratic Assembly candidate actually won in the City of West Bend, an area so conservative voters once threw their state senator out of office for not passing a constitutional amendment to cap taxes.

Somehow Republicans need to apply a tourniquet to the wound Donald Trump has inflicted. Keep in mind, Trump lost Wisconsin's Republican primary to Texas Sen. Ted Cruz; clearly Republicans had deep reservations about his fitness to govern. (Trump ended up winning the state in the general election, of course, but that just goes to show that Hillary Clinton's popularity in Wisconsin rivaled that of vegetarian bratwurst.)

If even a sliver of those wealthy, high-income Republicans uncomfortable with Trump decide to stay home in November, it could remake Wisconsin politics. State conservatives need to change the subject quickly to avoid being linked to Donald Trump.

Or as your local Republican state senate candidate will likely refer to him, "Donald Who?"