The Black by-election was a 'vote of confidence', Labor says — but has it turned a grip on power into a stranglehold?

Two-and-a-half years into the job as premier, and it appears Peter Malinauskas can do very little wrong in the eyes of South Australian voters.

For the second time in eight months, his government has claimed a prized seat from the Liberal Party.

Incumbent governments don't traditionally win by-elections, but as of Saturday night Labor had secured a two-party preferred swing towards it of more than 13 per cent, flipping Black from blue to red.

There's still a significant number of early votes that won't begin to be counted until Monday — a quirk unique to South Australian politics — but the ABC's chief elections analyst Antony Green has declared Liberal candidate Amanda Wilson is too far behind to catch up.

It was also a big night for the Greens' Sarah Luscombe, who further eroded the Liberal vote — attracting around 15 per cent in counting so far.

The victory installs Alex Dighton as Labor's 28th MP in the Lower House, extending the party's dominance over the Liberals, who now hold 13 seats.

But as stunning as this result is for the government, it perhaps says more about the state of the Liberal party.

Opposition leader Vincent Tarzia did his best to hide his disappointment when he addressed the party faithful to concede defeat.

He also acknowledged the man he replaced as leader, David Speirs.

"It's important to recognise that David has obviously achieved a lot in his time as the former member for Black," Mr Tarzia said.

"That's certainly a message that's been sent to all of us."

Lose the battle, win the war?

Right up until polls closed on Saturday, the "million-dollar question" all political pundits were asking was what impact Mr Speirs would have on the vote.

In early August, the former South Australian Liberal leader was vying to be the alternative premier.

Since then, he quit as opposition leader, alleged he was the victim of a "deepfake" video that appeared to show him snorting from a plate, was charged with drug offences, resigned from parliament triggering the by-election, and faced court for the first time on Friday where he is yet to enter a plea on one drug charge.

Despite all that, he remains widely popular in his electorate — and is viewed as having been a competent local member during his decade-long career as their representative in parliament.

But he also hasn't made it easy for Mr Tarzia in his early tenure as leader of the South Australian Liberal Party.

In September, Mr Speirs declared the Liberals faced "more of a Mount Everest than a Mount Lofty" ahead of the 2026 state election and warned the party would go backwards.

In the case of Black, he was right.

Mr Tarzia was desperate to steady his party's ship by holding the seat; now his job is even harder.

To lose two by-elections in less than eight months to the government is an anomaly, almost an aberration.

Then there's the raw electoral maths of such a result.

The Liberals are down to just 13 MPs in the Lower House — 11 away from forming government.

But on Saturday night, Mr Tarzia was readying for the fight ahead.

'Vote of confidence invested in us'

Party insiders are hopeful that the defeat will put a full-stop to the Speirs-era, and the party can move forward.

Some of the post-election analysis on where things went wrong for the Liberals will inevitably turn to who they picked as candidate — Holdfast Bay Mayor, Amanda Wilson.

She ran a strong campaign, buoyed by her party's pledge of $11 million to build a seaside pool at Hallett Cove.

But she was hammered by Labor for not living in the electorate.

And some Black voters who live within the City of Holdfast Bay local government area weren't all that impressed with having their rates raised to help pay for the Jetty Road upgrade at Glenelg.

Backed by the well-oiled campaign machine of the Labor Party, Alex Dighton made few errors along the way.

But aside from promising to open a 24/7 pharmacy in the electorate, Labor's strategy was largely to focus on what the government was doing across the board — particularly on health.

It appears voters have chosen to reward the Malinauskas government for its efforts so far.

The result is even more remarkable given the government has only just started to show signs it has turned the corner on reducing record ramping, its key 2022 election pledge.

The premier knows there's still a long way to go until the state goes the polls in March 2026.

"Tonight is really a night for this community, the people of Black," Mr Malinauskas told a jubilant Labor crowd on Saturday night.

"When we wake up tomorrow morning, we get back to work."

But only Labor will be waking up with a spring in its step.