The US has been gripped by cold weather in recent weeks, but pundits say it is in Texas where hell has truly frozen over.
District 9 of the state senate has for three decades been considered out of reach for Democrats.
The electorate voted resoundingly in favour of US President Donald Trump when it went to the polls in 2024, with a margin of about 17 points.
A 20-point margin separated GOP candidate Kelly Hancock from his Democrat rival at the last state senate election in 2022.
But in a recent election, that trend was overturned.
A blue wave swept the electorate with a 14-point swing to the Democrats.
For some Republicans, it is a worrying sign.
First, catch me up
Texas Republican Kelly Hancock resigned from his seat in the state's Senate on June 18 to take up a new role as chief clerk of the Texas Comptroller of Public Accounts.
A special election was scheduled for November 4, in which three candidates (a Democrat and two Republicans) vied for the seat, which encompasses part of Fort Worth.
[EXTERNAL: Special election results]
Democrat Taylor Rehmet, a labour union leader and veteran, amassed 47.57 per cent of the votes, but it was not quite enough to secure him the win.
According to state laws, if no candidate receives 50 per cent of the vote, a runoff election is held between the top two candidates.
It meant Republican Leigh Wambsganss was still in the race, and despite having only received 35.94 per cent, she had good reason to expect to pip Mr Rehmet.
Her GOP rival had drawn 16.49 per cent of votes in the special election — if his voters' preferences flowed to her, it would be enough for a narrow win.
After some additional campaigning between Mr Rehmet and Ms Wambsganss, Texans in District 9 returned to the polls on January 31.
Remarkably, the Democratic candidate increased his share by almost 10 points, with voters shooting him to a 57.21 per cent share of the tally – a lead of more than 14 points.
[EXTERNAL: Runoff results]
Why is it a big deal?
Even a narrow win would have been remarkable, given that the electorate has been a Republican stronghold for decades.
Mr Rehmet's win by a 14-point lead was "a huge political earthquake", said Matt McDermott, a Democratic strategist.
Even several ringing endorsements by Mr Trump proved insufficient in convincing conservative voters to turn out and vote for Ms Whambsganss.
Democrats say the outcome shows voters are motivated to push back on the president and his party allies.
"This victory is a warning sign to Republicans across the country," Democratic National Committee chairperson Ken Martin wrote in a statement on Saturday.
"Tonight's results prove that no Republican seat is safe."
The win is also part of a broader story where some have over-performed in special elections since Mr Trump returned to office.
That trend kicked off in March, when the party prevailed in a Pennsylvania electorate it had not held in a century, and continued through to November when it claimed contests from Maine to California.
Zohran Mamdani, an unapologetic Democratic Socialist, was elected mayor of New York City in a race that saw the highest voter turnout in 50 years.
Does the result affect Trump?
Not directly.
As a state senator, Mr Rehmet will not be voting on federal laws brought before Congress, so he will not become a hurdle to Mr Trump in that regard.
But Democrats have celebrated this win as adding to their building momentum, which is threatening to disarm the president by the end of the year.
Americans will go to the polls in November for the midterm elections.
That is when voters will decide the makeup of the House of Representatives and a third of the Senate in Congress.
As a rule of thumb, the party that the sitting president belongs to usually loses House seats at midterm elections.
This has had Mr Trump worried for months, because Republicans cannot afford to lose many seats if they are to hold onto their House majority and therefore their ability to pass laws without negotiating with Democrats.
[LINK: US House party breakdown] To insulate against this, he has urged Republican governors to change electoral maps in their states to give their party advantages in November.
Democratic leaders, particularly in California, have fought back by making similar changes in their favour.
While the GOP has so far gained a slight edge in the redistricting battle, it is not yet clear whether this will make any difference in who ends up with control of Congress.
[LINK: Gerrymandering results]
The other side of the coin
Politicians may be using the runoff election results as a barometer for what to expect at the midterms, but they do not necessarily form the most accurate comparison.
As prominent Republican Florida Governor Ron DeSantis pointed out on social media, "special elections are quirky".
They tend to have lower voter turnouts than usual, which was the case for this race.
There were fewer than 100,000 ballots cast. That is just a third of the turnout recorded at the 2022 general election for the same seat.
Mr Rehmet got the largest share of the votes at both elections, but a lower Republican turnout could account for his huge margin in the runoffs.
Local politics likely also played a role.
Commentary on social media has suggested Ms Wambsganss's activism history alienated some voters.
Earlier this decade, she pushed for independent school district boards to be stacked with far-right candidates.
Laney Hawes, an activist against book bans in Texas schools, said on X this was "what really brought Dems & Reps together ... to vote against Leigh Wambsganns (sic)".
How did Trump react?
The president immediately distanced himself from the loss.
"I don't know, I didn't hear about it. Somebody ran — where?" he replied when asked about the result at his Mar-a-Lago estate in Florida on Sunday.
"I'm not involved in that; that's a local Texas race. You mean I won by 17, and this person lost? Things like that happen."
Mr Trump had heaped praise on Ms Wambsganss as recently as the day prior.
Other Republicans, including Ms Wambsganss, have described the outcome as a "wake-up call".
"The Democrats were energised," the bested candidate said in a statement. "Too many Republicans stayed home."
ABC/AP
