By Eric Bradner, CNN

(CNN) -- The Democratic-backed candidate won a seat Tuesday on Wisconsin's Supreme Court, another warning signal for the GOP that led Republican Gov. Scott Walker to tweet that the party is "at risk of a #BlueWave" in November.

Liberal Rebecca Dallet trounced conservative Michael Screnock in the race for a 10-year term on the state's high court. Screnock conceded the race, and results continued to trickle in late Tuesday showing Dallet with a double-digit lead.

The candidates did not run with party affiliations. The state Democratic Party machinery worked to help Dallet win and reveled in her victory. It was the first time a liberal candidate who wasn't an incumbent had won a seat on the seven-member court in 23 years.

On the heels of a major swing in Democrats' favor in a state Senate race in Wisconsin earlier this year, it's the latest indication that the political ground has shifted since President Donald Trump and Republican Sen. Ron Johnson won there in 2016.

Walker, who is up for re-election to a third term next fall, tweeted that the results were another sign that the GOP is in trouble.

"Tonight's results show we are at risk of a #BlueWave in WI. The Far Left is driven by anger & hatred -- we must counter it with optimism & organization. Let's share our positive story with voters & win in November," he tweeted.

In another tweet, Walker added, "Big government special interests flooded Wisconsin with distorted facts & misinformation. Next, they'll target me and work to undo our bold reforms. We need to keep moving #WIForward & make sure a #BlueWave of outside special interest money doesn't take us backward."

It's the latest in a series of major election victories for Democrats.

The run began in November 2017, when they handily won the Virginia governor's race and nearly flipped control of a state assembly that had been two-thirds Republican.

Even more worrying for Republicans is that Democratic candidates have had success in areas Trump won easily in 2016, including a special election for a US Senate seat in Alabama in December, and then in March when Democrat Conor Lamb won a House seat in western Pennsylvania's deep-red steel country.

Tom Perez, the Democratic National Committee chairman, called the Wisconsin results "the latest example of the unprecedented energy we're seeing across the country."