A Liberal MP is under fire from her own side after posting a happy snap congratulating Labor’s new Dunkley MP.

Zoe McKenzie, who holds the outer Melbourne seat of Flinders, posted the selfie to Instagram late on Saturday.

It was intended as congratulations to Labor’s Jodie Belyea, who won Saturday’s byelection in the adjacent seat. The picture shows a smiling McKenzie, who replaced former Coalition minister Greg Hunt as the member for Flinders in 2022, with her arm around Belyea.

“Congratulations Jodie Belyea,” McKenzie captioned the photo of the pair.

“You have been a good friend to women across the Mornington Peninsula. Look forward to working with you in looking after paradise!”

But the simple message brought a quick smackdown from some of McKenzie’s Liberal colleagues.

“An absolute act of naivety,” one senior Liberal source told The Australian.

“Unforgivable,” said another.

A senior Liberal told the newspaper they were “floored” at the happy snap.

“To say the anger among the ranks is palpable would be an understatement,” they said.

“We are at war with Labor. To think this new breed of Liberal thinks otherwise is infuriating.”

“We are going to run a campaign against Jodie Belyea at the next election, what do we do now?”

In a further twist, McKenzie’s husband is Rodrigo Pintos Lopez. He resigned on Sunday as chief-of-staff to Victorian Opposition Leader John Pesutto.

Belyea won Saturday’s byelection despite a 3.5 per cent swing against the government at the poll.

While the swing was largely in line with those against ruling parties at other byelections, Deputy Prime Minister Richard Marles said the results would be looked at closely ahead of the May budget and next federal election.

“We will be very careful in hearing that message and we’ll go through these results in a lot of detail to really understand what is being said here,” he told ABC Radio on Monday.

“We want to learn everything we can from this result.”

Marles said the government’s win also proved that voters backed changes to the stage-three tax cuts.

“It is clear the policies we put in place around cost of living, particularly Labor’s tax cuts, were well received, but we will continue to work hard on our cost of living issues right through until the next election,” he said.

Labor’s primary vote was up almost 1 per cent at Saturday’s byelection, but the Liberals had a 6.5 per cent swing to them on the same measure.

Prime Minister Anthony Albanese said that result was due to right-wing parties such as One Nation not running a candidate.

“That explains the bump in the Liberal primary vote,” he told ABC Radio.

“The Liberal Party under Peter Dutton, the lesson that they’ve taken from the last election is to become more conservative, more right wing.”

But Victorian Liberal senator Jane Hume said there were promising signs for the next federal election from Saturday’s vote.

“By the time [the votes are fully counted] it may be the most marginal seat in the state, and there were some real green shoots, I think, for the Liberal Party there for the first time in about a decade,” she said.

“We always knew this was going to be a tough byelection for the Liberal Party – we haven’t held the seat of Dunkley with its current boundaries ever before, and at the last election our primary vote went down.

“We’ve certainly got our tails up after the weekend.”

Hume said there were also positive signs for the Liberals in other Melbourne electorates such as Kooyong and Higgins, which they lost in 2022.

“All of these seats are marginal and they are in the mix,” she said.

“Like every election, we will target marginal seats and Dunkley is now a marginal seat.”

The byelection was triggered by the death of former Labor MP Peta Murphy.

-with AAP