The Democrats scored a big win in the Wisconsin State Senate on Tuesday.
Patty Schachtner secured a 9-point win over her GOP opponent in a special election for District 10.
It was triggered when the GOP incumbent Sheila Harsdorf resigned to take a job in the Wisconsin Dept. of Agriculture, Trade and Consumer Protection.
Why's it significant?
Because this was a very Republican district. According to Ballotpedia, it had been held by the GOP since 2000 and President Trump won it by 17 points in the 2016 presidential election.
It adds to the growing weight there will be a "blue wave" in the 2018 mid-terms, with Schachtner's win the 34th pickup for the Democrats in the 2018 cycle, whereas Republicans have flipped just four seats, the Chicago Tribune reports.
Scott Walker isn't happy then?
No. The Republican governor is facing re-election himself this year and the Washington Post suggests he's looking a whole lot more vulnerable now than he did on Tuesday.
But even if he wins re-election, his job running the state will be markedly more difficult if Republicans lose control of either the State Senate or the State Assembly.
This is perhaps why he went on a Twitter binge around midnight on Tuesday, calling the Democrats' win a "wake-up call" before extolling the achievements of his administration.